Engine Controls - Tests W/codes: Other Mercedes-Benz S-class W140 facelift

HFM-SFI

The HFM-SFI system is equipped with a self-diagnostic capability for trouble shooting. Vehicles are tested reading stored Diagnostic Trouble Codes (DTCs). Diagnostic modules are now referred to as diagnostic module (OBD-II). Diagnostic information can be retrieved using a generic scan tool or Hand-Held Tester (HHT) (965 589 00 01 00) and Multiplexer Cable (965 589 00 40 00). Control module will permit testing approximately 10 seconds after engine starting procedure is completed.

ME-SFI

The ME-SFI system checks its inputs and outputs and recognizes possible faults. Diagnostic information is read using a generic scan tool or Hand-Held Tester (HHT) (965 589 00 01 00) and Multiplexer Cable (965 589 00 40 00).

Operating Conditions

When faults are recognized and stored, operating conditions are also stored to help in diagnosing a fault. If a fault is recognized, the following operating conditions are stored

1. Adaptation Value Of Air/Fuel Mixture
2. Coolant Temperature
3. Engine Load State
4. Engine Speed
5. Fault Code
6. Intake Manifold Pressure
7. Lambda Control State
8. Vehicle Speed

CHECK ENGINE Light

CHECK ENGINE light is illuminated if fault was already stored during last trip. Faults which no longer occur are automatically erased after no more than 40 warm-up phases. A warm-up phase is completed if coolant temperature is less than 95°F (35°C) at engine start and coolant warms up to more than 176°F (80°C).

CHECK ENGINE light will go out if no fault is detected during 3 trips with the same operating conditions. A trip is completed if

1. All checks and function chains of exhaust-relevant faults completed at least once since engine start.
2. Time elapsed after engine start is more than 20 minutes.
3. Engine temperature is more than 19.4°F (-7°C).
4. Engine speed greater than 500 RPM.

Function chains are check sequences activated by the ME-SFI control module for secondary air injection, adjustable camshaft timing, purging and leak check of EVAP system.

If engine misfiring occurs, CHECK ENGINE light will immediately flash. This relates to fault codes P0300 through P0312. For other faults, CHECK ENGINE light will illuminate and remain on. If a fault is recognized, substitute values are used for vehicle operation.

To prevent consequential faults from being stored, if a faulty signal is detected during a trip and the appropriate fault code is stored, all checks are aborted where this signal is required as a comparison parameter.

PRETEST CONDITIONS

Note. Information for ME-SFI equipped vehicles is not available.

Start and run engine until engine oil temperature is 176°F (80°C). Turn air conditioning off. Ensure shift lever is in Park. Check all fuses and replace as necessary. Verify battery voltage is 11-14 volts.

SERVICE PRECAUTIONS

Note. Information for ME-SFI equipped vehicles is not available.

When servicing S320 vehicles, the following precautions must be followed when using Hand-Held Tester (HHT)

1. DO NOT connect or disconnect Hand-Held Tester (HHT) to vehicle with ignition on. Voltage is supplied to HHT through data link connector.
2. ALWAYS connect multiplexer cable to HHT first, then to data link connector.
3. DO NOT connect HHT to 110-volt or 220-volt power source.
4. Keep HHT away from strong magnetic fields, such as welding equipment.
5. DO NOT expose HHT to water, brake fluid, thinners, etc.

RETRIEVING CODES

Note. Information for ME-SFI equipped vehicles is not available.

Note. During Diagnostic Trouble Code (DTC) retrieval, CHECK ENGINE light will illuminate continuously.

DTC memory can be cleared using generic scan tool or Hand-Held Tester (HHT). After clearing DTC memory, using generic scan tool or HHT, give "end" command and turn ignition off for approximately 5 seconds. Turning ignition off for approximately 5 seconds allows DTC memory to be overwritten. An alternative method of clearing DTC memory is to disconnect vehicle battery.

Disconnect vehicle battery. Stored DTCs are now erased. Stored DTCs can also be erased using Hand-Held Tester (HHT) (965 589 00 01 00) and Multiplexer Cable (965 589 00 40 00). Follow equipment manufacturer's instructions.