Self Diagnosis - Theory & Operation (N63): Other BMW X6 E71

1.1 Catalyst Monitoring

P0420/P0430

1.1.2 Monitoring function

If all monitoring conditions are fulfilled, then a special defined A/F-modulation will be done.

The first lean to rich cycle of the test is only used to establish an average voltage value of the downstream sensor voltage. During subsequent cycles the calculation of the OSC is based on the accumulated value of the difference between the average value of the previous lean to rich cycle and the measured instantaneous voltage during the current lean to rich cycle.

The relation of the deviation between the current downstream-sensor-signal to the average value of the downstream-sensor-signal is a lead for catalyst condition.

The catalyst system is considered malfunctioning, if after a specified number of monitoring cycles the average of the accumulated deviation exceeds a threshold. The corresponding fault code is stored.

Scheme 29

1. monitoring two cross criteria (calculated sensor signal has to cross the mean value characteristic curve twice)
2. monitoring of delta threshold for minimum and maximum of trim control set-point (O2 _CAT is a calculated value, taking O2 rear signal as a basis)
3. difference of mean value of the calculated sensor signals related to one period to the next one [(O2_CAT_MV n ) -(O2_CAT_MV n-1 )]

1.2 Heated Catalyst Monitoring

A heated catalyst is not embedded.

1.3 Misfire Monitoring

P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0307, P0308, P1396

1.3.1 Monitoring function

The method of engine misfire detection is based on evaluating the engine speed fluctuations. The engine torque is a function of engine speed, engine load and the moment of inertia.

In order to detect misfiring at any cylinder, the torque of each cylinder is evaluated by metering the time between two ignitions, which is a measure for the mean value of the speed of this angular segment. A change of the engine torque results in a change of the engine speed.

It is also an influence of the load torque, such as the influences of different road surface, e.g. pavement, potholes etc. If the mean engine speed is measured, influences caused by road surfaces have to be eliminated.

This method consists of following main parts

Data acquisition

The duration of the crankshaft segments is measured continuously for every combustion cycle.

Segment time adaptation (P1396)

Within a defined engine speed range and during fuel cut-off, the segment time adaptation, instead of the misfire detection, is carried out. This is done in three engine speed ranges. If the segment time adaptation is out of the maximum adaptation range, failure P1396 is stored.

With progressing adaptation the sensitivity of the misfire detection is increasing. The adaptation values are stored and taken into consideration for the calculation of the engine roughness.

Calculation of the engine roughness

The engine roughness is derived from the differences of the segment durations.

Different statistical methods are used to distinguish between normal changes of the segment duration and the changes due to misfiring.

Correction of the engine roughness value

The adaption during firing operation (fuel-on adaption) learns systematic differences of the calculated engine roughness between the individual cylinders depending on the current operating point of the engine.

The learned fuel-on adaptation values are used to correct the engine roughness values to improve the overall signal-to-noise range.

Determination of misfiring

Misfire detection is performed by comparing the engine roughness threshold value with the engine roughness value. If the threshold is exceeded, single misfire is detected. The decision, whether the threshold shortfall of the irregular running is evaluated, depends on the monitoring conditions.

1.3.2 Statistics, Fault Processing

Emission Limit

If the sum of cylinder(s) misfire counters within 1000 revolutions is 4 times exceeding a predetermined value during a driving cycle, or during the first 1000 revolutions, the fault code for emission relevant misfiring is temporary stored. If the following driving cycle is also above the emission limits, the MIL will be switched on and a cylinder selective or global fault will be stored.

Catalyst Damage

If the weighted sum of cylinder(s) misfire counters within 200 revolutions is exceeding a predetermined value the fault code for catalyst damage relevant misfiring is stored and the cylinder with the highest rate will be switched off and the MIL will be switched on immediately. If two cylinders are switched off and the misfire rate is still above the damage limits, MIL is flashed immediately. If one of the cylinder selective counters is exceeding the predetermined threshold the following measures take place

1. The lambda closed loop system is switched to open-loop condition.
2. The cylinder individual fault code is stored or if multiple cylinders, then the global fault code is set.
3. Fuel supply of the misfiring cylinder(s) is cut-off (per customer request)
4. No downstream fuel trim. All misfire counters are reset after each interval.

1.4.1 EVAP Canister Purge Solenoid (CPS) Functional Check

P0440

1.4.1.1 Monitoring function

The diagnosis is used for the functional test of the CP solenoid (CPS).

The test consists of two checks.

The first check of the CPS is based on the active charcoal filter (ACF) amount. The "canister load diagnosis" is calculated permanently during tank purge.

If amount is above threshold ok is detected.

If amount is below threshold, the next step will be performed.

During the next check, the CPS is evaluated based on manifold pressure deviation, while motor is running in idle speed. The CPS is opened for a short time and the manifold pressure is monitored during the CPS opening. Additionally the deviation of lambda-controller (rich mixture) is monitored.

After this check has been enabled it is requested during each idle speed phase as long as the monitoring conditions are met. This is repeated as long as a result has been reached. This check is not bound to one idle speed phase, but can be distributed to several idle speed phases.

If the CPS is detected to be not ok three times, the error is set.

1.4.2 EVAP System Leak Measurement (Module DM-TL)

P0442, P0456, P1434, P1447, P1448, P1449

1.4.2.1 Monitoring function - Leak Detection

P0442, P0456

The evaporative system monitoring permits the detection of leaks in the evaporative system with a diameter of 0.02 inches and up.

By means of a Diagnostic Module Tank Leakage (DM-TL), an electrical actuated pump located at the atmospheric connection of the evaporative canister, a pressure test of the evaporative system is performed in the following order

During the Reference Leak Measurement, the electrical actuated pump delivers through the reference restriction. The engine-management system measures the pump's electrical current consumption in this section.

Scheme 30

During the Leak Measurement, the electrically actuated pump delivers through the charcoal canister into the fuel-tank system. The pressure in the evaporative system may be up to 2.5 kPa depending on the fuel level in the tank. The engine-management system measures the pump's electrical current consumption. A comparison of the currents of the reference leak measurement and the leak measurement is an indication of the leakage in the tank.

Scheme 31

0.02 inch diagnosis, very small leak

P0456

The first step of the diagnosis is the reference measurement, the result of the pump reference current is stored (picture in chapter a). After the solenoid switches, the venting system is pressurized (picture in chapter b). In the small leak measurement the small leak threshold is reached, if the leak is smaller than 0.04 inch and then the small leak measurement phase follows. When the DM-TL current reaches the reference current within the very small leak time, the system is tight (leak smaller than 0.02 inch), otherwise a very small leak between 0.02 - 0.04 inches is detected.

0.04 inch diagnosis, small leak

P0442

The first step of the diagnosis is also the reference measurement, the result of the pump reference is stored (picture in chapter a). After the solenoid switches, the venting system is pressurized (picture in chapter b). In the small leak phase (time) the pump current must reach the small leak threshold 1

Small leak threshold 1 = idle current pump + K1 x (reference current - idle current). Factor K1 is between 0.16 and 0.28 depending on the characteristic current value of the pump (reference current - idle current), this value is various in every pump.

If the small leak threshold 1 is not reached in the small leak time, the small leak threshold 2 must be reached in an additional time small leak threshold 2 = reference current pump - K2 x (reference current - idle current). Factor K2 is between 0.60 and 0.80 depending on the characteristic current value of the pump (reference current - idle current).

If the small leak threshold 2 is also not reached, a leak > 0.04 inches is detected.

In the diagram below is the typical current of a tight system, a 0.02 inch leak, and a leak > 0.04 inches.

Scheme 32

Scheme 33

1. After the test the remaining pressure in the evaporative system is bled off through the charcoal canister by switching off the pump and solenoid.

1.4.4.1 EVAP - DMTL Valve Electrical Check

P2418, P2419, P2420

1.4.4.2 EVAP - DMTL Heater Electrical Check

P240A, P240B, P240C

1.4.4.3 EVAP - DMTL Pump Electrical Check

P2400, P2401, P2402

1.4.4.4 EVAP - Purge Control Valve Electrical Check

P0444, P0458, P0459

1.5 Secondary Air System Monitoring

No Secondary Air System built in.

1.6.1 Lambda Adaptation

P0171/P0174, P0172/P0175

1.6.1.1 Monitoring function

The fuel system diagnosis uses two different monitors. The first one is the evaluation of the percentage of the long term fuel adaption. The other one is the evaluation of the percentage of the physical limits of the short term fuel trim.

The monitoring of the short term fuel trim is active during all engine states except during deceleration fuel cut-off. The evaluation of the long term fuel trim is active during its learning process and is not active during canister purge phases of the evaporative system. Because of this an additional learning process can be started in case of large deviations of the short term fuel trim and the evaluation can run. After the enable conditions are met different counters are started for both evaluations. If no condition is present the end diagnostic counter will decrement from a calibratable value to zero and a passing decision is made.

If a lean condition is present and total fuel control is above the calibratable threshold two timers are started. If the lean threshold counter exceeds the calibratable threshold before the reset timer has decrement from calibratable threshold to zero a lean error is set.

If a rich condition is present and total fuel control is below the calibratable threshold two timers are started. If the rich threshold counter exceeds the calibratable threshold before the reset timer has decremented from a calibratable threshold to zero a rich error is set.

The time counters are increased while "lambda controller" or "lambda adaptation" exceed minimum or maximum threshold.

The error is detected as soon as one of the time counters reaches its maximum value.

1.6.1.2 Similar conditions function

When the engine management system recognizes a failure in the misfire or fuel systems, the engine management system is required to record the conditions present when the fault occurred. These conditions recorded include engine speed, engine load (MAF), and warm up status of the first event that resulted in the storage of a code. These conditions stored are referred to as similar conditions .

If the similar conditions are met without a failure in the misfire or fuel system, the flag will be set to 1. If this flag is set, the driving cycle counter for that failure can be decrement.

The code and stored freeze frame conditions may be erased if similar conditions are not encountered during the next 80 driving cycles which immediately following the initial detection of the malfunction.

The MIL may be extinguished after three sequential driving cycles in which similar conditions have been encountered without an exceeding the thresholds of the fuel system diagnostic.

Variable list

VARIABLE LIST REFERENCE

1.6.2 Trim Control Plausibility Monitoring

P2096/P2098, P2097/P2099

1.6.2.1 Monitoring function

The trim control plausibility monitoring detects a high deviation of the I-share of lambda trim control. If it exceeds given thresholds the following malfunction is detected

1. fuel trim above limit

If the above mentioned malfunction is detected, the corresponding fault code is stored.

AIR FUEL MIXTURE SPECIFICATION

1.6.3.1 Monitoring function

A small proportion of the short term fuel deviation is used for diagnostic injector aging and is stored as injector adaption value in a separate map. The values of the separate map will be renewed every time the mileage achieves 497 miles.

A fault is stored if the injector adaption exceeds a calibratable minimum or maximum threshold.

1.6.4.1 Monitoring function - High Pressure System

High pressure system diagnosis: P302A/P302B, P302C/P302D, Fuel mass plausibility check: P3283/P3285, P3284/P3286

For gasoline direct fuel injection a high pressure fuel control system is necessary for fuel preparation and metering (Scheme 34) The low fuel pressure from the fuel pump module within the tank is increased by the high pressure fuel pump and adjusted to a desired set-point fuel pressure.

The high pressure fuel system consists of a common fuel rail for all high pressure Piezo-injection valves, a fuel rail pressure sensor, a high pressure fuel pump with a built-in fuel volume control valve and overpressure-valve.

In dependence of engine load and engine speed, high pressure has to be adjusted to values between 5 and 20 MPa. Therefore the fuel pressure in the rail is measured and controlled with help of the fuel volume control valve. According to the desired fuel-mass and fuel pressure set-point value the pre-control calculates the driver-signal for the fuel volume control valve. This calculated driver-signal is additionally controlled by a closed loop control using the measured fuel pressure and the desired set-point value as input.

Scheme 34

The high pressure system diagnosis consists of a rationality check and analyses in principle the difference between the measured fuel pressure and the set-point fuel pressure and the output of the pressure controller. If an adjustable limit is reached, additionally the output of the long term fuel trim and the lambda controller is taken into account.

The pressure deviation is defined as the difference of the set-point and the measured value. (Which means a pressure higher than the set-point leads to a negative deviation and vice versa).

A not adjustable fuel rail pressure (to high) is detected if the pressure deviation or the output of the pressure controller is below a calibrated (negative) threshold and one of the output values of the lambda control (which are lambda controller and long term fuel trim) is below a calibrated (negative) threshold. (Which means the air fuel ratio tends to be too rich without correction). If these conditions are fulfilled for a calibrated period of time, a malfunction is detected and a maximum fault high pressure system monitoring is set.

A not adjustable fuel rail pressure (to low) is detected if the pressure deviation or the output of the pressure controller is above a calibrated threshold and one of the output values of the lambda control is above a calibrated threshold. (Which means the air fuel ratio tends to be too lean without correction). If these conditions are fulfilled for a calibrated period of time, a malfunction is detected and a minimum fault high pressure system monitoring is set.

The fuel mass plausibility diagnosis checks the plausibility of the high pressure sensor signal.

A too high pressure sensor signal is detected if the pressure deviation or the output of the pressure controller is below a calibrated (negative) threshold and one of the output values of the lambda control (which are lambda controller and long term fuel trim) is above a calibrated threshold. (Which means the air fuel ratio tends to be too lean without correction). If these conditions are fulfilled for a calibrated period of time, a malfunction is detected and a maximum fault high pressure sensor monitoring is set.

A too low pressure sensor signal is detected if the pressure deviation or the output of the pressure controller is above a calibrated threshold and one of the output values of the lambda control (which are lambda controller and long term fuel trim) is below a (negative) calibrated threshold. (Which means the air fuel ratio tends to be too rich without correction). If these conditions are fulfilled for a calibrated period of time, a malfunction is detected and a minimum fault high pressure sensor monitoring is set.

1.6.4.2 Monitoring function - Pressure Range Check

P303A/P303B, P303C/P303D

Additionally the pressure is monitored regarding the absolute range of the pressure values. If the pressure value is below a calibrated threshold, a minimum fault code is stored (P303C/P303D). If the pressure value is above a calibrated threshold, a maximum fault code is stored (P303A/P303B).

1.6.5.1 Monitoring function

The diagnosis of the fuel rail pressure sensor consists of electrical checks (signal range checks)

If the measured voltage from the fuel rail pressure sensor exceeds the upper calibration limit, a short circuit to battery or cable breakage is detected and a maximum fault is set.

If the measured voltage from the fuel rail pressure sensor exceeds the lower calibration limit, a short circuit to ground is detected and a minimum fault is set.

1.6.5.2 Fuel Rail Pressure Sensor Electrical Check

P0192/P3250, P0193/P3251

1.6.5.3 Volume Control Valve Electrical Check

P0003/P1281, P0004/P1282

1.6.5.4 Volume Control Valve Relay Output Electrical Check

P10C3, P10C2, P10C1

1.6.6 Injection Deactivation

P140E, P142E, P142F

1.6.6.1 Monitoring function

The injection deactivation is a diagnosis to protect the catalysts from overheating. In fact it is an additional fuel pressure diagnosis with a very short diagnostic time and an early reaction with deactivation of some injectors. Additional there is an evaluation of the fuel tank level. If the tank level is low there will be a change of the DTC to provide better information's for the workshop.

Scheme 35

The diagnosis evaluates first an air-fuel deviation. This check analyses the difference between the measured air fuel ratio and the set-point air fuel ratio and analyses the short term fuel trim. Both checks detect only the lean side of mixture. If a lean deviation occurs the diagnosis compares the difference between measured pressure and the set-point of the high pressure and the absolute value of the high pressure sensor with a threshold or checks the absolute value of the low pressure sensor. Then a DTC is set and the reaction is the shut-off of an amount of injectors. This reaction avoids overheating of the catalysts. The decision of which DTC is stored will be affected by the fuel tank level (= 0 litre).

1.6.7.2 Fuel Level Sensor Electrical Circuit Continuity Check

P0462/P2067, P0463/P2068

1.6.7.2.1 Monitoring function

The signal of the fuel level sensor is monitored concerning the valid range. This range depends on the used fuel level sensor.

If the left or right fuel level sensor signal is above the upper threshold, a short circuit plus is detected. If the left or right fuel level sensor signal is below the lower threshold, an appropriate fault code for the left or right sensor is set.

FUEL LEVEL SENSOR FUNCTION CHART

1.6.7.3 Fuel Level Sensor Signal Correlation Check

P144B

1.6.7.3.1 Monitoring function

The engine management system has the capability to calculate (sum up) the fuel consumption. For the fuel level sensor correlation check, this calculated consumption is compared with the decreasing of the fuel level signal. When the calculated value for fuel consumption reaches an appropriate and predetermined value (e.g. five gallons), the calculated fuel consumption is compared to the difference of the fuel level as indicated by the fuel level sensors (between starting calculation and current). In case the difference is greater than the applicable threshold value, a fuel level sensor fault is detected and an appropriate fault code is set.

If a fault is present, the OBD II EVAP leak monitor will run using a substitute value of 85% total fuel tank volume.

The 85% substitute value will assure that in every case the required 0.020 inch leak is detected by the OBD II system.

MONITORING FUNCTION CHART

Scheme 36

1.7.1.1 Upstream Oxygen Sensor - Short Circuit Monitoring

P0131/P0151, P0132/P0152

1.7.1.1.1 Monitoring function

The oxygen sensor circuit monitoring detects the following malfunctions by evaluating the error information received from oxygen sensor microcontroller

1. short circuit of sensor signal to battery voltage
2. short circuit of sensor signal to ECU ground

If one of the above mentioned malfunctions is detected, the corresponding fault code is stored.

BATTERY VOLTAGE SPECIFICATION

1.7.1.2 Upstream Oxygen Sensor - Open Circuit Monitoring

P112C/P112D, P2626/P2629, P2243/P2247

1.7.1.2.1 Monitoring function

The oxygen sensor circuit monitoring detects the following malfunctions by evaluating the error information received from oxygen sensor monitoring functions

VOLTAGE REFERENCE CHART

If one of the above mentioned malfunctions is detected, the corresponding fault code is stored.

1.7.1.3 Upstream Oxygen Sensor - Signal Controller Monitoring

P3022/P3023, P3024/P3025

1.7.1.3.1 Monitoring function

This function will detect an error during the initialization and/or operation of a WRAF sensor controller through SPI communication. Information communicated from the Basic Software (BSW) is used for initialization and communication between application software (ASW) and the controller. This is used to determine if the function is working properly.

After an ECU reset, the WRAF sensor controller is started and the diagnosis determines the time until the initialization, has been performed in the allowed time. If not successful, then a DTC will be stored. If this is successful, then the difference is checked between the present error counter and the stored value of this error counter at ECU reset, (switching from Key "OFF" to Key "ON") or at clearing error memory and after each function call, in case a difference between both counters was found.

If there is a difference, another counter is incremented. If this counter is higher than a threshold, a SPI communication error is stored.

COMMUNICATION ERROR CHART

All of the above checks are performed internal to the ECU.

1.7.1.4 Upstream Oxygen Sensor - Signal Activity Check

P2414/P2415

1.7.1.4.1 Monitoring function

The oxygen sensor signal activity check monitors if the sensor is attached to the exhaust pipe and whether the exhaust is sampled correctly (no leakage). A malfunction is detected if the oxygen sensor voltage is above a threshold (shows too lean mixture in part load or full load)

If the above mentioned malfunction is detected, the corresponding fault code is stored.

MONITORING FUNCTION CHART

1.7.1.5 Upstream Oxygen Sensor - Swapped Sensors Check

P0040

1.7.1.6 Upstream Oxygen Sensor - Active Signal Check (Shift to lean/rich)

P2195/P2197, P2196/P2198

1.7.1.7 Upstream Oxygen Sensor - Signal Dynamic Monitoring (Slow Response)

P0133/P0153

1.7.1.7.1 Monitoring function

The oxygen sensor signal dynamic monitoring detects greater deviations of the dynamic behavior of the sensor signal compared to the nominal behavior, controlled by the lambda controller.

The change of the dynamic behavior is caused by problems of the electrical connection (e.g. open circuit), extreme aging of the sensor or a low sensor temperature which slows down the sensor compared to the nominal behavior.

The monitoring is based on an amplitude criterion, i.e. the relation between the amplification of the oxygen sensor and the model is monitored and detects the following malfunction

1. sensor signal too slow

If the above mentioned malfunction is detected, the corresponding fault code is stored.

MONITORING FUNCTION CHART

1.7.1.8 Upstream Oxygen Sensor - Signal Monitoring During DFCO

P2297, P2298

1.7.1.8.1 Monitoring function

The oxygen sensor signal monitoring during deceleration detects if the oxygen sensor signal is not plausible during fuel cut-off. A malfunction is detected if the oxygen sensor voltage is outside the "normal operating voltage range during DFCO (deceleration fuel cut off)" ( (Scheme 37)below).

If the oxygen sensor signal voltage is within the range "operating voltage during DFCO not plausible" ( (Scheme 37)below) the signal is not plausible. If the above mentioned malfunction is detected, the corresponding fault code is stored.

MONITORING FUNCTION CHART

If the oxygen sensor signal voltage is above a threshold during fuel cut-off or below a threshold then the open circuit diagnostic function is triggered (see chapter ' UPSTREAM OXYGEN SENSOR - OPEN CIRCUIT MONITORING '). The fault processing continues in this function.

Scheme 37

1.7.1.9 Upstream Oxygen Sensor - Heater Monitoring

P3026/P3027, P0135/P0155, P165F/P166F

1.7.1.9.2 Monitoring function

The diagnosis strategy is based on a statistical evaluation of the oxygen sensor ceramic temperature over a pre-defined number of monitoring cycles.

The oxygen sensor ceramic temperature shall be obtained indirectly via the measured internal resistance of the sensor.

If the sensor is not ready after a defined time (e.g. 30 sec after start)* the sensor is set to forced readiness mode and the Upstream Oxygen Sensor Heater Monitoring is started.

Three cases can appear

1. sensor temperature is invalid (no measurement of sensor temperature possible because of an ECU internal (electrical) failure) --> P165F/P166F is stored
2. sensor temperature is below a threshold --> normal failure detection time
3. sensor temperature is below a threshold for sensor activation --> immediate failure storing

A low sensor temperature can be caused by a weak heater or a open circuit in the temperature measurement line (line UN). After a low sensor temperature has been detected, the general temperature failure is stored (P3026/P3027). Then the open circuit diagnosis is triggered to check, if an open circuit in line UN is present. If there is an open circuit, then open circuit fault code (P2243/P2247) is stored (see chapter ' OXYGEN SENSOR MONITORING - OPEN CIRCUIT ' and picture below). If there is no open circuit present, then the heater fault code is stored (P0135/P0155).

)* For exact values please have a look at the summary table!

SENSOR TEMPERATURE SPECIFICATION

Scheme 38

1.7.1.10 Upstream Oxygen Sensor - Heater Circuit Monitoring

P0030/P0050, P0031/P0051, P0032/P0052

1.7.1.10.1 Monitoring function

The oxygen sensor heater circuit monitoring detects the following malfunctions by evaluating the error information received from the power stage

1. Heater O2 sensor front short circuit to battery voltage
2. Heater O2 sensor front short circuit to ground
3. Heater O2 sensor front open circuit

If one of the above mentioned malfunctions is detected, the corresponding fault code is stored.

MONITORING FUNCTION CHART

1.7.2.1 Downstream Oxygen Sensor - Circuit Monitoring

P0137/P157, P0138/P158, P0140/P0160

1.7.2.1.1 Monitoring function

The oxygen sensor electrical monitor detects the following malfunctions

1. O2 Sensor rear signal short circuit to battery voltage
2. O2 Sensor rear signal short circuit to ground
3. O2 Sensor rear signal open circuit

If one of the above mentioned malfunctions is detected, the corresponding fault code is stored.

MONITORING FUNCTION CHART

1.7.2.2 Downstream Oxygen Sensor - Signal Dynamic Check During DFCO

P013E/P014A

1.7.2.2.1 Monitoring function

Sensor signal dynamic monitoring is performed at fuel cut-off during coasting conditions. To enable the diagnosis the voltage of the O2 sensor rear has to be above a threshold before entering DFCO (deceleration fuel cut-off).

After entering DFCO the signal falls from fuel trim correction set-point (e.g. 0.68 V) to a voltage near 0 mV. A malfunction is detected, if the sensor signal is not below a threshold after a short time on DFCO. This short time is needed to guarantee a completely purged exhaust pipe.

If this malfunction is detected, the corresponding fault code is stored.

MONITORING FUNCTION CHART

1.7.2.3 Downstream Oxygen Sensor - Dynamic/Transition Time in Sensor Midpoint Range Monitoring

P013A/P013C

1.7.2.3.1 Monitoring function

This function monitors the transition time in sensor midpoint range of the downstream sensor voltage. When a fuel cut-off phase starts, the following steps will be executed

1. sensor voltage must be above a threshold (signal must be rich enough, to measure the transition time)

Remark: Usually the signal starts at fuel trim control set-point (e.g. 0.68 V)

1. sensor voltage value is stored (= "start-value")
2. transition time measurement is started, when the signal is at 70% of start value

Remark: The measurement start and stop-value are relative to the start value, to measure always the transition time around the sensor midpoint range

1. transition time measurement is finished, when the signal is at 38% of start value
2. measured transition time is corrected over mass air flow

The transition time is represented by a cycle counter. This transition time is measured over a defined number of fuel cut-off phases. The minimum value after the defined number of fuel cut-off phases is compared with a failure threshold.

If this value is above a threshold, a malfunction is detected and the corresponding fault code is stored.

TRANSITION TIME REFERENCE

Scheme 39

1.7.2.4 Downstream Oxygen Sensor - Signal Activity Check

P114A/P114C, P114B/P114D

1.7.2.4.1 Monitoring function

The diagnosis monitors the downstream sensor voltage during active fuel trim controller p-share. If the fuel trim control is active, the downstream sensor voltage has to be in range between a maximum and minimum threshold. If all monitoring conditions are fulfilled a mass air flow integral is incremented (MAF_1, see picture below). After reaching its threshold the integral is reset and incremented again as long as the conditions are fulfilled.

If the voltage is outside the mentioned band of maximum and minimum threshold)*, a second mass air flow integral is incremented simultaneously (MAF_2, see picture below). If this integral is over a threshold before the first integral reaches its limit, a malfunction is detected.

This fault will be stored too, if the downstream sensor voltage does not switch to rich before the integral reaches a threshold after a fuel cut-off phase

If one of the above mentioned malfunctions is detected, the corresponding fault code is stored. Referring to this failure entry the " DOWNSTREAM ACTIVE TEST " is triggered to decide the root cause of the downstream sensor behavior (see chapter " DOWNSTREAM OXYGEN SENSOR - SIGNAL CHECK ").

DOWNSTREAM SENSOR VOLTAGE CHART

)* For exact values of thresholds etc. please have a look at the summary table!

1.7.2.5 Downstream Oxygen Sensor - Signal Check (Stuck lean/rich, Swap)

P2270/P2272, P2271/P2273, P0041

1.7.2.5.1 Monitoring function

Downstream Active Test

This monitor is an enhancement of the Downstream Oxygen Sensor - Signal activity check and the Trim Control Plausibility Monitoring. Its purpose is to determine, why the rear sensor signal is not plausible.

The monitor will only be enabled, if a fuel correction fault was detected and a malfunction code is stored (P2096 - P2097 - P2098 - P2099)

OR

if the rear sensor signal activity check has detected, that the rear sensor signal is very rich or very lean and the corresponding malfunction fault code is stored (P114A - P114B - P114C - P114C)

If one of the listed fault codes is stored, this diagnosis will be enabled to determine if the root cause of the malfunction is due to a stuck signal or characteristic line shift of the upstream O2 sensor or due to a stuck signal or a system malfunction (i.e. vacuum leak, injector, etc.) of the downstream O2 sensor.

If it has been determined that the upstream O2 signal was the root cause of the fuel correction fault, the appropriate DTC will be stored along with the fuel correction or with the downstream sensor signal activity DTC (see chapter ' UPSTREAM OXYGEN SENSOR - ACTIVE SIGNAL CHECK (SHIFT TO LEAN/RICH) ').

If it has been determined that the downstream sensor signal was the root cause of the fuel correction fault, the appropriate DTC (see table below) will be stored along with the fuel correction or with the downstream sensor signal activity DTC.

This function will also detect, if the oxygen sensor wire harness has been cross connected, i.e., Bank 1 with Bank 2. When this failure is present, the downstream sensor voltages of bank 1 and 2 are on opposite limits.

If one of the above mentioned malfunctions is detected, the corresponding fault code is stored.

DOWNSTREAM SENSOR STUCK RICH CHART

1.7.2.6 Downstream Oxygen Sensor - Heater Plausibility Monitoring

P0141/P0161

1.7.2.6.1 Monitoring function

For proper function of the oxygen sensor, the sensor element must be heated.

A non functioning heater delays the sensor readiness for closed loop control and thus influences emissions.

The monitoring strategy is based on the comparison of the O2 sensor resistance to a threshold in conditions where the exhaust temperature is low enough to cause an increase of internal resistance in cases where the heating power is insufficient.

The cooling energy of the exhaust gas is calculated and compared to a calibrated threshold, and the diagnosis is activated if the cumulated cooling energy is equal or exceeds the threshold.

Then the O2 sensor resistance is compared to a threshold, and if the resistance higher than the threshold, an O2 sensor heater malfunction is detected and the corresponding fault code is stored.

Corresponding fault code

FAULT CODE REFERENCE

1.7.2.7 Downstream Oxygen Sensor - Heater Circuit Monitoring

P0036/P0056, P0037/P0057, P0038/P0058

1.7.2.7.1 Monitoring function

The purpose of this monitor is to detect errors within the O2 Sensor Heater Circuit. The signal for the O2 sensor heater is pulse-width modulated. The signal of the power stage is monitored internally by the integrated circuit (IC). This IC can distinguish between three symptoms

1. Heater O2 sensor rear short circuit to battery voltage
2. Heater O2 sensor rear short circuit to ground
3. Heater O2 sensor rear open circuit

If one of the above mentioned symptoms is present, a malfunction is detected and the corresponding fault code is stored.

BATTERY VOLTAGE SPECIFICATION

1.7.3 Closed Loop Lambda Control - Enable conditions

Closed loop lambda control is enabled (with a delay) at the start of a driving cycle and can be temporary or permanently deactivated during the driving cycle. The turn-on delay at the start of a driving cycle is described by the following enable conditions

1. the upstream oxygen sensor operability is detected i.e. the upstream HO2'S operating temperature has been reached
2. a calibrated delay time, after end of engine start, has elapsed

Only for linear Lambda Sensor - Disable conditions

1. the A/F ratio set-point value lies below oxygen sensor's measurable limit

Closed loop lambda operation is further deactivated during a driving cycle when any of the following conditions are fulfilled

1. during fuel cut-off or cylinder shut-off and immediately afterwards till a calibrated integrated mass air flow threshold is exceeded
2. the mass air flow is below a calibrated threshold that leads to the minimum possible injection time

1.8 Exhaust Gas Recirculation (EGR) System Monitoring

An Exhaust Gas Recirculation (EGR) System is not built in.

1.9 Positive Crankcase Ventilation (PCV) System

The PCV-architecture of the turbo charged new 8-cylinder engine N63 is designed as a two way ventilation system. This two way ventilation system is designed in two separate connections between crankcase and intake manifold (please (Scheme 40)).

Connection (1) is used at part load and ends after the turbo charger in the intake manifold. The PCV-valve used in this path is fastened directly to the crankcase. A disconnection or leakage in this part of the PCV-System is indicated by a rough or stalling engine and will result in reaction within fuel system (fuel trim deviation) or misfire system. In both cases a fault code will be stored.

Part load

Scheme 40

Connection (2) is used at high load and ends before the turbo charger in the intake manifold. A disconnection of the end of the line, which is fixed to the crank case, including a separate check valve, isn't possible without demolition of the concerned parts. The connection fixed to the air duct can be removed.

A disconnection of this end of line is indicated by a rough or stalling engine and will result in reaction within fuel system (fuel trim deviation), air mass flow plausibility or misfire system. In all cases a fault code will be stored

Full load

Scheme 41

1.10.1 Thermostat Monitoring

P0128

1.10.1.1 Monitoring function

The coolant thermostat monitoring is done to detect a slow warm-up due to heat losses through thermostat and radiator. It is based on the comparison of the measured ECT sensor signal and the calculated ECT model (TCO_SUB).

The ECT model calculation is depending on engine load and ambient air temperature.

A malfunctioning coolant thermostat is detected, if the calculated ECT model has exceeded the threshold 1 (P0128) and the measured ECT sensor signal remains below threshold 2 (P0128).

Before a malfunctioning coolant thermostat is entered into failure memory, the conditions concerning low load, coasting duration and low vehicle speed, intake air temperature during the monitoring are checked. If the monitoring conditions are met, the coolant thermostat is entered into failure memory. Otherwise the coolant thermostat monitoring is inhibited for this driving cycle.

Example of Monitoring Method

Scheme 42

A comparison between the measured engine coolant temperature (ECT) and the fault detection criteria temperature is done after a specific time interval. The interval itself is based on the engine coolant temperature model.

As soon as the model temperature exceeds 94°C and all other monitoring conditions are fulfilled at the same time, a valid diagnosis occurs.

At that time, if the measured engine coolant temperature is higher than Fault detection criteria (thermostat regulation temperature -20 Kelvin), the thermostat is concluded as normal thermostat.

On the contrary, if the measured coolant temperature is lower than Fault detection criteria (thermostat regulation temperature -20 Kelvin), the thermostat is concluded as opened stuck thermostat.

The thermostat regulation (opening) temperature is determined by the hardware. It is normally 105°C ±4 Kelvin. The fault detection criteria for the thermostat is therefore 81°C.

THERMOSTAT REGULATION TEMPERATURE CHART

1.10.1.2 Thermostat Electrical Check (Comprehensive component attendant to thermostat)

P0597, P0598, P0599

1.10.2.1 Engine Coolant Temperature Electrical Check

P0117, P0118

1.10.2.1.1 Monitoring function

The purpose of this diagnosis is to detect electrical faults of the sensor signal. The input signal is analog from a NTC and has to be in a calibratable range. Short circuit to ground can be detected immediately. Short circuit to voltage battery or open circuit is detected, if conditions of intake air temperature and time after start are fulfilled. If an error symptom is detected, the error counter is de-bounced.

Error Symptoms

1. Short circuit to voltage battery or open circuit
2. Short circuit to ground

1.10.2.2.1 Monitoring function

The purpose of this diagnosis is to detect an implausible gradient on the engine coolant temperature signal. The diagnostic function checks whether the difference between one measured engine coolant temperature value and the succeeding value is too high.

Error Symptom

1. Engine coolant temperature signal gradient error

1.10.2.3.1 Monitoring function

The purpose of this diagnosis is to detect a stuck coolant temperature signal. The diagnostic function checks if after a variation of the calculated coolant temperature also a variation of the measured coolant temperature is detected. The range of required variation depends on engine coolant temperature at engine start.

For RBM handling the Cold Start Denominator will be considered.

Error Symptom

1. Engine coolant temperature signal stuck error

1.10.2.4.1 Monitoring function

The purpose of this diagnosis is to detect a engine coolant temperature signal that is stuck in high range. The diagnostic function checks if after a certain time the engine has been stopped, the engine coolant temperature has reached a plausible (low) value, i.e. the engine has cooled down.

If the measured engine coolant temperature at engine start is above a calibratable threshold and the diagnosis conditions are fulfilled, the error is set. The threshold depends on intake air temperature at start and the time engine was stopped.

For RBM handling the Cold Start Denominator will be considered.

Error Symptom

1. Engine coolant temperature signal stuck in range error

1.10.3.1 Radiator Outlet Temperature Electrical Check

P00B4, P00B3

1.10.3.1.1 Monitoring function

The purpose of this diagnosis is to detect electrical faults of the sensor signal. The input signal is analog from a NTC and has to be in a calibratable range. Short circuit to ground can be detected immediately. Short circuit to voltage battery or open load is detected, if conditions of intake air temperature and time after start are fulfilled. If an error symptom is detected, the error counter is de-bounced.

Error Symptoms

1. Short circuit to voltage battery or open circuit
2. Short circuit to ground

1.10.3.2.1 Monitoring function

The purpose of this diagnosis is to detect an implausible gradient on the radiator outlet temperature signal. The diagnostic function checks whether the difference between one measured radiator outlet temperature value and the succeeding value is too high.

Error Symptom

1. Radiator outlet temperature signal gradient error

1.10.3.3.1 Monitoring function

The diagnosis is based on monitoring the alternation of radiator outlet temperature signal, positive and negative changes in three phases.

Just after start, if ECT and IAT are below an adjustable threshold, a too high ROT can be detected by comparison of ECT at start and ROT at start.

During warm - up phase (long term check, with no error detection) the diagnosis will only run if ECT at start and IAT lies within a tunable range after engine start. Minimum and maximum ROT are continuously updated from engine start, after first being initialized to ROT at power up. The difference between these two values is also calculated. When this value exceeds a minimum threshold then the diagnosis is finished with a positive rationality check result.

After opening of thermostat, the long term check with error detection starts. The error detection is based on a change of radiator outlet temperature after the opening temperature of the thermostat is reached and following the vehicle/engine is driven under certain conditions (vehicle speed, part load, engine speed, opening of thermostat) for a delay time. However, should one condition drop below the threshold or the engine exit part load state during this tunable period, then the timer is reinitialized/incremented.

For RBM handling the Cold Start Denominator will be considered.

1. Radiator outlet temperature too high after start
2. Radiator outlet temperature is not plausible

1.10.3.3.2 Monitoring conditions

1. battery voltage in range
2. engine coolant temperature at start in range
3. intake air temperature at start in range
4. engine speed above threshold
5. engine coolant temperature above threshold
6. engine state part load
7. vehicle speed above threshold
8. for certain time and additional waiting time

Input parameters for monitoring

1. engine coolant temperature
2. radiator outlet temperature
3. engine speed
4. intake air temperature
5. vehicle speed
6. actuation pulse-width modulation of thermostat

1.11 Cold Start Emission Reduction Strategy Monitoring

All parameters, that are relevant during the cat heating phase, are monitored by standard monitoring functions

e.g. MSD80-N54

Scheme 43

To fulfill the legal requirements, the monitoring of the idle speed is now extended to the cold start phase. In case of an error, the specific DTC's

1. P1561 Cold Start Idle Air Control System RPM lower than expected
2. P1562 Cold Start Idle Air Control System RPM higher than expected

are set. Look at illustration Idle speed control

During cat heating, it is essential to make sure, that enough thermal energy is applied to the catalyst to heat it up as quick as possible.

Therefore it is target to limit the ignition timing to the earliest possible value during the cat heating phase.

If there would be a demand for more torque and therefore for an advanced ignition timing beyond the limits, the engine would be allowed to stall instead of fulfilling the demand.

The torque limits are calibrated the way that the emissions stay below 1.5 times of the limits.

Scheme 44

Known System

During normal driving, the ignition timing desired torque corresponds to the air mass desired torque, which determines the ignition timing. During the cat heating phase, the cat heating torque is added to the air mass desired torque, resulting in a higher reference air mass torque.

The efficiency, desired torque divided by the reference torque, determines the ignition timing.

New System (BMW-development)

The earliest possible ignition timing is determined by the limitation of the torque reserve to a minimum value during the cat heating phase. For this, the required minimum cat heating torque is subtracted from the reference air mass torque. The thus reduced efficiency leads to a safe ignition retard and limits the ignition timing during the cat heating measures.

Limitation of ignition timing to the earliest possible ignition timing during the cat heating phase by limitation of torque reserve to the minimum required torque reserve.

Scheme 45

The maximum ignition timing after cold start with new BMW method

Scheme 46

1.12 Air Conditioning (A/C) System Component Monitoring

The BMW air conditioning system is not OBD-relevant.

1.13.1.1 Variable Camshaft Timing (Vanos) (detection of mechanical IVVT error)

P0012/P0022, P0015/P0025

The BMW-Vanos is a combined hydraulic and mechanical camshaft control unit, managed by the ECU. The double Vanos allows the engine to control valve-timing continuously for both intake and exhaust camshafts. The electronically control of the Vanos positions is dependant on engine speed, load and temperature.

The diagnosis is monitoring the correct mechanical function of the variable camshaft timing. The diagnosis carries out a continuous rationality check of the Vanos function. If a malfunction is detected, an error bit will be set and sent to the Error management module. This module produces the final information for setting the corresponding DTC.

The diagnostic strategy for inlet and exhaust camshaft is identical.

1.13.1.2 Monitoring function

In this diagnosis module the difference between the actual and target position of the Vanos units ("control deviation") is checked. If the calculated difference between these two positions exceeds the established threshold, a counter is started. The counter is incremented twice per crank revolution (but not exceeding 10 msec-rates).

If the counter exceeds a limit (also adjustable), a rationality fault (DTC) is stored.

The control deviation diagnosis has got an interface to the Rate-Based Monitoring module.

1. In-use monitor performance Ratio: The incrementing of the numerator, denominator, and the ratio calculation for the Variable Camshaft Timing monitor is executed by the Rate-Based Monitoring module. Like all monitors for which a standardized track and report in-use performance is required, the Variable Camshaft Timing monitor reports to the RBM-module via status flags.
2. Conditions for incrementing the Numerator: The numerator is incremented if and only if the monitor is not inhibited due to stored faults and the diagnostic has been performed and a fault would have been detected.
3. Conditions for incrementing the Denominator: The denominator is incremented if the monitor is not inhibited due to stored faults, the general driving conditions have been fulfilled and all additional physical conditions for incrementing have been fulfilled.

1.13.2 Camshaft Position Sensor (CMP)

The purpose of the diagnosis is to detect when the camshaft reference position is outside the designed range relative to the engine position from crankshaft and to detect a signal which is not valid.

The diagnostic strategy for inlet and exhaust camshaft is identical.

1.13.3.1 Monitoring function - Crankshaft Camshaft Synchronization

P0017

The diagnosis is performed at every edge of the selected camshaft signal and at the reference gap of the CKP sensor signal. The distance (in crankshaft degrees) between events is compared to the stored camshaft signal pattern. For each signal edge the distance must fit to the designed position in the pattern plus/minus a tolerance. The tolerance is expanded by the range of the variable valve timing, when the camshaft is not in lock position.

The following malfunctions are detected

1. for synchronization selected CMP sensor signal not valid P0017

The monitor eliminates with every event the edges from the list of all 6 cam edges, which are not insides the pattern. If a calibrated number of camshaft signal edges were detected and the list of remaining signal edges contains at least one edge, the camshaft signal is valid for synchronization. If no edge is left in the list, synchronization failed and is started again. If a calibrated number of synchronizations failed, the error is delivered to the error management. Afterwards, and only if synchronization fails with the intake camshaft, the same procedure is started with another camshaft.

1.13.4 Crankshaft Position Sensor (CRK)

The purpose of this diagnostic is to check the integrity of the crankshaft sensor signal and/or electrical malfunctions. (Open line, SCG, SCVB)

1.13.4.2 Monitoring function - Missing CRK Sensor Signal

P0335

Detection of missing crankshaft signal is based on the detection of CAM signals without any CRK signal. If no CRK signal at all is received and if 12 or more CAM edges are detected, the symptom is "missing signal".

1.13.4.3 Monitoring function - No plausible CRK Signal

P0336

Detection of implausible crankshaft signal is based on the detection of CAM signals without receiving correct CRK signal. If 12 or more CAM edges are detected (eg. 2 working cycles), without valid synchronization of the crankshaft, then "no plausible CRK signal" is detected and delivered to the error management.

1.13.4.4 Monitoring function - Wrong Tooth Number

P0370

A teeth counter is incremented at every falling edge of the CRK sensor signal. If plus or minus two teeth are detected during the last 360° CRK. In this case the de-bounce counter will be incremented. If the counter exceeds a limit, a "CRK tooth number" error is delivered to the error management.

1.13.4.5 Monitoring function - Sync Error

P138F

If more then two teeth plus or minus are detected, the reference gap position is ambiguous and CRK looses synchronization. In that case a CRK sync de-bounce counter will be incremented. If the counter exceeds a limit, a "CRK sync" error is delivered to the error management.

1.13.4.6 Monitoring function - Tooth Period

P0370

The detection of a tooth period error is done by an acceptance window. The expected tooth period is multiplied and divided with an engine speed dependency factor. The result is a bottom and a top limit of tooth period, in which the destination of two falling edges of the electrical signal has to occur. If a tooth period is not valid, the tooth period error de-bounce counter will be incremented. If the counter exceeds a limit, a "CRK tooth per" error is delivered to the error management.

1.13.5 Camshaft Position Actuator Electrical Check

P0010/P0020, P2088/P2092, P2089/P2093

P0013/P0023, P2090/P2094, P2091/P2095

1.14.1 Strategy

Principle

1. Sensors that can affect emissions or are used to monitor other component/system are monitored for circuit continuity and short to battery voltage and/or to ground using high and low voltage signal limit.
2. Actuators that can affect emissions or are used to monitor other component/system are monitored by power stage voltage check for valid signals.
3. For some of sensors or actuators, plausibility checks are included to ensure proper operation of the components.

1.14.1.1 Monitoring strategy for sensors

Sensor signals out of a defined range are regarded as circuit malfunctions shorted to BATT, GND or Open circuit.

1.14.1.2 Monitoring strategy for actuators

Invalid actuator output signals at power stage are regarded as circuit malfunctions shorted to BATT, GND or Open circuit.

1.14.1.3 Rationality check

Components are checked for the integrity of their values. This is accomplished by the use of a model or other sensor inputs. If a component does not function as expected or the integrity is in question (values are not within a threshold) it is considered out of range/plausible.

1.14.2.1.1 Monitoring function

The purpose of this diagnosis is to detect electrical faults as defined in OBDI requirements. The input signal is a CAN message of instrument cluster. If an error is detected by the instrument cluster, the error symptom is sent via CAN to the ECU. The ECU then de-bounces the error and stores it in the error management.

Error Symptoms

1. short circuit to battery or open line
2. short circuit to ground

1.14.2.2 Ambient Air Temperature (AAT) Signal Plausibility Check

P0071

1.14.2.2.1 Monitoring function

In order to monitor the ambient air temperature (AAT), a cross-check using different temperature sensors is realized. For the temperature sensors to indicate a similar value, it is essential that the engine/vehicle has been cooled down for a minimum amount of time.

Error detection

If the absolute temperature difference [1]

(ambient air temperature (AAT) - intake air temperature at throttle (IAT_THR)

AND

the absolute temperature difference [2]

(ambient air temperature (AAT) - engine coolant temperature (ECT)) exceed a threshold, the ambient air temperature sensor has a malfunction.

Otherwise the sensor works properly.

In other words: For error detection, the differences between the sensor values (as shown below) are compared to threshold values.

IF

I AAT - IAT_THR I > THD1

&

I AAT - ECT I > THD2

THEN

ERR_AAT = 1

ELSE

ERR_AAT = No

1.14.3.1.1 Monitoring function

This diagnosis checks IAT integrity for a plausible range and signal stuck.

For the range detection, IAT has to be within coolant temperature and ambient temperature window. If IAT is outside of the range plus an offset, the error symptom is set and the error counter is de-bounced.

If the vehicle was driven with a certain vehicle speed for a calibratable time (IAT sensor cool down) and afterwards the vehicle was in idle for a calibratable time (IAT sensor hot up), the IAT signal must have moved. If the signal has not moved after a calibratable number of cool down/hot up phases, a stuck intake air temperature signal is detected and the error is de-bounced.

For RBM handling the Cold Start Denominator will be considered.

Error Symptoms

1. Signal too high
2. Signal too low
3. Signal not plausible

1.14.3.2 Intake Air Temperature Sensor Electrical Check

P0112/P00AC, P0113/P00AD

1.14.3.2.1 Monitoring function

The purpose of this diagnosis is to detect electrical faults as defined in OBDI requirements. The input signal is analog from a NTC and has to be in a calibratable range. Short circuit to ground can be detected immediately, short circuit to voltage battery or open load after a delay time. If an error symptom is detected, the error counter is de-bounced.

Error Symptoms

1. Short circuit to voltage battery or open load
2. Short circuit to ground

1.14.4.1.1 Monitoring function

This diagnosis checks charge air temperature integrity for a plausible range and signal stuck.

For the range detection, charge air temperature has to be within coolant temperature and ambient temperature window. If charge air temperature is outside of the range plus an offset, the error symptom is set and the error counter is de-bounced.

If the vehicle was driven with a certain vehicle speed and load (mass air flow) for a calibratable time (charge air temperature sensor hot up) and afterwards the vehicle was in idle for a calibratable time (charge air temperature sensor cool down), the charge air temperature signal must have moved. If the signal has not moved after a calibratable number of cool down/hot up phases, a stuck charge air temperature signal is detected and the error is de-bounced.

For RBM handling the Cold Start Denominator will be considered.

Error Symptoms

1. Signal too high
2. Signal too low
3. Signal not plausible

1.14.4.2.1 Monitoring function

The purpose of this diagnosis is to detect an implausible jump discontinuity or implausible gradient or implausible offset on the intake air temperature signal. If a jump discontinuity is located, the error is not de-bounced and is registered in error management. If an implausible gradient or offset is detected, the error is de-bounced.

Error Symptoms

1. Signal gradient not plausible
2. Signal too high

1.14.4.3 Charge Air Cooler Temperature Sensor Electrical Check

P007C/P00A2, P007D/P00A3

1.14.4.3.1 Monitoring function

The purpose of this diagnosis is to detect electrical faults as defined in OBDI requirements. The input signal is analog from a NTC and has to be in a calibratable range. Short circuit to ground can be detected immediately, short circuit to voltage battery or open load after a delay time. If an error symptom is detected, the error counter is de-bounced.

Error Symptoms

1. Short circuit to voltage battery or open load
2. Short circuit to ground

1.14.5.1.1 Monitoring function

The ETC - H-Bridge IC continually checks the ETC, if there is a short circuit to battery voltage or ground. In addition the IC is able to detect over-temperature. This is performed internally to the ECU.

1.14.5.2 Electronic Throttle Control (ETC) Motor Control Performance

P11AA/P11AB, P16D0/P16D1

1.14.5.2.1 Monitoring function

This diagnosis is able to detect a too slow or jammed actuator.

One part of the diagnosis checks, whether the pulse width modulation signal (PWM) used to control the throttle flap, exceeds the permissible maximum value for longer than the designated time. If this time is exceeded, the appropriate DTC will be stored.

The second part of the diagnosis checks, whether the difference between the actual throttle value and the set-point value exceeds the allowed value

[f(throttle position gradient)]. If such behaviour is detected, a DTC is stored.

1.14.5.3 Electronic Throttle Control (ETC) Composite Error

P1417, P1455

If

P11AA active OR

P16D0 active OR

P2100 active OR

P16BA active OR

P1632 active OR

P1633 active OR

P169A active OR

P169B active OR

P16BC active OR

P16BE active OR

P16CA active OR

P16CC active OR

P0121 active OR

P0122 active OR

P0123 active OR

P0221 active OR

P0222 active OR

P0223 active OR

P115F active

then

the composite error P1417 will be stored.

If

P11AB active OR

P16D1 active OR

P210A active OR

P16BB active OR

P16AA active OR

P16AB active OR

P16AD active OR

P169C active OR

P16BD active OR

P16BF active OR

P16CB active OR

P16CD active OR

P0226 active OR

P0227 active OR

P0228 active OR

P212B active OR

P212C active OR

P212D active OR

P117E active

then

the composite error P1455 will be stored.

1.14.5.4.2 Monitoring function - ETC Start Check

P16BA/P16BB, P169A/P16AD

The diagnosis is performed at the beginning of every driving cycle at ignition "Key ON" position, but is stopped without error entry, if the enable conditions are not fulfilled.

It checks, whether the values at limp-home position are in range and if the throttle flap reaches a defined set-point in a certain time.

1.14.5.5 Throttle Position Sensor (TPS) Plausibility Check

P0121/P0226, P0221/P212B

1.14.5.5.1 Monitoring function

In case an electrical error (P0122/P0227, P0123/P0228, P0222/P212C, P0223/P212D) or an ratio error (P115F/P117E) at one of the throttle units is detected, the remaining position sensor is checked against a model based on engine temperature, engine load and intake air temperature. If the deviation between model value and measured value exceeds the calibrated threshold, the corresponding error is set.

1.14.5.6 Throttle Position Sensor (TPS) Ratio Check

P115F/P117E

1.14.5.6.1 Monitoring function

The correlation of the two position sensors built into the throttle body is checked by this diagnosis. Therefore the following calculation is made

abs (angle sensor 1 - angle sensor 2) > threshold

If the difference is larger than the threshold, the error is stored in the error memory.

1.14.5.7 Throttle Position Sensor Electrical Check

P0122/P0227, P0123/P0228, P0222/P212C, P0223/P212D

1.14.5.8.1 Monitoring function - Check of Supply Voltage

P164C, P1625

The supply voltage of the pedal position sensors is monitored for deviation of its nominal value of 5V to ensure that the measured pedal value is correct.

1.14.5.8.2 Monitoring function - Double Error

P1224

The double error is set, if both pedal value sensors are detected as faulty (i.e. by range check error on both sensors, supply voltage error on one and range check error on the other sensor or supply voltage error an both sensors).

1.14.6.1.1 Monitoring function

This diagnosis monitors the stability of the idle speed during cold start and in warm operation.

During cold start

If the actual idle speed is not within a calibratable range, above or below the idle speed set-point then the failure criteria is fulfilled. The appropriate DTC will be stored.

Warm operation

If the actual idle speed is not within a calibratable range, above or below the idle speed set-point and the ISC integrator is equal the maximum or minimum threshold limit.

The ISC integrator is a measurement for the regulated deviation to reach the set-point idle speed and is limited to an upper and lower limit.

Scheme 47

Variable list

EMS PARAMETER DESCRIPTION

1.14.7.1.1 Monitoring function

Based on the boost pressure sensor upstream of the throttle, the throttle position, cam position and the current engine speed an observer of the manifold pressure and air mass flow values is used. The main function of this observer is to calculate the manifold pressure and the air mass flow in the cylinder. The calculated air mass flow at the throttle depends mainly of the throttle position. The calculated air mass flow into the cylinder depends mainly of the manifold pressure. The main measured value which is used to control this observer is the air mass flow meter, hence an air mass flow control is used.

Two plausibility checks are used

For the mass air flow plausibility diagnosis, the ratio of the calculated air mass flow at the throttle and the measured air mass flow at the air mass flow meter is calculated. If this ratio exceeds certain calibrated limits, a fault code (MAF) is set.

For the manifold pressure diagnosis the ratio of the resulting air mass flow into the cylinder (based on MAP) and the calculated air mass flow at the throttle are calculated. If this ratio exceeds certain calibrated limits, a fault code (MAP) is set.

Scheme 48

In the monitoring conditions a limited dynamic condition is checked for engine speed an engine load. Only under steady state engine operating the diagnosis is possible due to dynamic effects.

To recognize dynamic engine operation (for example engine speed), the actual engine speed is compared with a moving mean value of the engine speed (PT1-behaviour). The difference between the actual engine speed and the moving mean value of the engine speed must not exceed a value, which can be calibrated. Also the time constant T of the PT1 term can be calibrated. The load dynamic is calculated identical to the engine speed dynamic.

Scheme 49

1.14.7.2 Ambient Pressure, Boost Pressure and Manifold Absolute Pressure

Ambient Pressure Sensor: P12B8, P12B9

Boost Pressure Sensor: P12A8/P12B6, P12A9/P12B7

Manifold Pressure Sensor: P12A4/P12A6, P12A5/P12A7

1.14.7.2.1 Monitoring function

For the monitoring of the air path pressure sensors (ambient (1x), boost (2x) and manifold (2x)) all measured values are compared to each other. If the engine is not running (engine speed = 0), all sensors must show the sum value.

After a calibratable time after engine stop the mean value of all sensors is taken as reference. If a pressure value is below or above a certain calibratable threshold compared to this mean value, a fault code is set.

Scheme 50

1.14.8.1 Manifold Absolute Pressure Sensor Electrical Check

P119B/P11AF, P119A/P11AE

1.14.8.1.1 Monitoring function

The purpose of this diagnosis is to detect electrical faults as defined in OBDI requirements. The input signal is analog and has to be in a calibratable range. If an error symptom is detected, the error counter is de-bounced.

Error Symptoms

1. Short circuit to voltage battery or open load
2. Short circuit to ground

1.14.9.1.1 Monitoring function

The air-mass meter HFM6 is able to recognize an internal fault. In this case, the HFM6 switches into the fault mode and remains in it until the internal fault is not longer present. In fault mode the pin state of the air mass flow signal is set to low and the pin state of the temperature intake air signal is set to high.

Error Symptoms

1. Self check: internal fault

1.14.9.2.1 Monitoring function

The purpose of this diagnosis is to detect electrical faults as defined in OBDI requirements. The input signal from the air-mass meter is digital. Therefore the pin state has to change from low to high and high to low with a certain frequency. If the pin state is not alternating, the error symptom is set and the error counter is de-bounced.

Error Symptoms

1. Short circuit to voltage battery or open load
2. Short circuit to ground

1.14.9.3.1 Monitoring function

This diagnosis checks temperature correction integrity for a plausible range. If the temperature correction signal is outside of the range, the error symptom is set and the error counter is de-bounced.

Error Symptoms

1. Signal too high
2. Signal too low

1.14.9.4.1 Monitoring function

The purpose of this diagnosis is to detect electrical faults as defined in OBDI requirements. The input signal from the air-mass meter is digital. Therefore the pin state has to change from low to high and high to low with a certain frequency. If the pin state is not alternating, the error symptom is set and the error counter is de-bounced.

Error Symptoms

1. Short circuit to voltage battery or open load
2. Short circuit to ground

1.14.9.5.1 Monitoring function

This diagnosis checks mass air flow for a plausible range. If the air mass flow is outside of the physical range, the error symptom is set and the error counter is de-bounced.

Error Symptoms

1. Signal too high
2. Signal too low

1.14.10.1 Vehicle Speed Sensor Signal Plausibility Check

P0503

1.14.10.1.1 Monitoring function

A vehicle speed signal plausibility error is detected if at calibratable engine speed-, mass air flow- and time thresholds the vehicle speed signal = 0.

Error symptom

MONITORING FUNCTION CHART

1.14.10.2 Vehicle Speed Sensor Signal Check

P0500

1.14.10.2.1 Monitoring function

A vehicle speed signal error is set if neither a vehicle speed signal is available from ECU-PIN nor a signal is received from CAN (11H/12H).

Error symptom

MONITORING FUNCTION CHART

1.14.11 Knock Sensor (KS)

P0326, P0327, P0328, P135B, P1327, P1328

P135F, P1329, P1330, P033B, P033C, P033D

1.14.11.1 Monitoring function

The purpose of the diagnosis is to detect faults of the knock sensor. Therefore the signal range and dynamics of a low pass filtered knock signal is checked.

If the signal range exceeds a upper or lower threshold a failure is detected.

An implausible knock signal is detected by using a statistical analysis. The difference between filtered knock signal and raw knock signal is estimated for a certain number of combustion cycles.

All error symptoms are de-bounced.

Error Symptoms

1. noise level above valid range
2. noise level below valid range
3. knock sensor signal not plausible

1.14.12.1 Supercharger Boost Sensor Electrical Check

P0237/P0241, P0238/P0242

1.14.12.1.1 Monitoring function

The purpose of this diagnosis is to detect electrical faults as defined in OBDI requirements. The input signal is analog and has to be in a calibratable range. If an error symptom is detected, the error counter is de-bounced.

Error Symptoms

1. Short circuit to voltage battery or open load
2. Short circuit to ground

1.14.13.3 Ambient Pressure Sensor Electrical Check

P2228, P2229

1.14.13.4 Ambient Pressure Sensor Rationality Check

P321E, P321F

1.15 Listing of all ECU Input and Output Signals

PIN DESCRIPTION