OBD-II
PCM detects malfunctions related to engine sensors or actuators. OBD-II continuously monitors emission related components and can store Diagnostic Trouble Codes (DTCs), 1st trip DTCs, freeze-frame data, 1st trip freeze-frame data and System Readiness Test (SRT) information. This data and DTC information can be retrieved to assist in diagnosing problems. Using the Malfunction Indicator Light (MIL) to access MIL codes is limited to code retrieval and fuel feedback monitoring, and is not recommended. It is recommended to use Generic Scan Tool (GST), or Nissan's CONSULT scan tool when performing self-diagnostic procedures, clearing PCM or performing a System Readiness Test (SRT).
When a malfunction is detected for the first time, the 1st trip DTC and 1st trip freeze frame data are stored in Powertrain Control Module (PCM) memory. However, in most instances, MIL will not be illuminated. If the same malfunction is detected on the next trip, MIL will be illuminated and a DTC is stored (2nd trip detection logic). If a misfire or fuel system malfunction should occur during 1st trip, MIL may be illuminated or flash. DTC and freeze-frame information will be stored to aid in diagnostics by specifying operating conditions when DTC was set.
FREEZE-FRAME DATA
Note. 1st trip freeze-frame data values can only be displayed with Nissan's CONSULT, and are not displayed on GST scan tool.
Freeze-frame data is a "snapshot" of the operating conditions present when a fault is detected by PCM. When a fault is detected for the first time, PCM stores the first trip DTC, along with first trip freeze-frame data. Only one set of freeze-frame data can be stored in PCM (either first trip freeze-frame data or freeze-frame data). There is no priority for first trip freeze frame data. It is updated each time a different first trip DTC is stored. If a fault is detected for the second time, first trip freeze-frame data is replaced with freeze-frame data.
Freeze-frame data is updated in order of priority. See FREEZE FRAME PRIORITY IDENTIFICATION table. If a priority 1 fault (misfire or fuel injection system malfunction) is detected in another trip when priority 2 freeze-frame data is already stored in PCM, priority 2 freeze-frame data will be replaced by priority 1 freeze-frame data.
Note. Only one 1st trip DTC and one freeze-frame data "snapshot" can be stored in PCM. If using GST, 1st trip DTC freeze-frame information may not be accessible. Use CONSULT to retrieve 1st trip DTC freeze-frame information.
| Priority | Items |
|---|---|
| 1 | Freeze Frame Data For Misfire DTC P0300-P0306, Fuel Injection System DTC P0171, P0172, P0174 & P0175 |
| 2 | (1) 2nd Trip Freeze Frame Data |
| 3 | 1st Trip Freeze Frame Data |
| (1) Not in priority 1. | |
| (1) | Not in priority 1. |
FREEZE FRAME PRIORITY IDENTIFICATION
RETRIEVING CODES USING MIL
Note. CHECK ENGINE or SERVICE ENGINE SOON light is now referred to as Malfunction Indicator Light (MIL).
Turn ignition on. Verify MIL is properly illuminated. If MIL does not illuminate, repair MIL circuit. See appropriate diagram in WIRING DIAGRAMS article. Turn mode selector switch on PCM fully clockwise. MIL should turn off. Wait 2 seconds, and turn mode selector fully counterclockwise. System is now in Diagnostic Test Mode II. Retrieve Diagnostic Trouble Codes (DTCs) by observing MIL, and counting the number of flashes. Record all codes set and then go to appropriate test procedure. MIL DTC numbering is different than CONSULT or GST DTC numbering. See appropriate DIAGNOSTIC TROUBLE CODE (DTC) IDENTIFICATION table.
MIL Code Display
MIL Code is a 4 digit number indicated by 2 separate 2 digit numbers flashed by MIL. The 2 separate numbers are separated by a pause (.9 second). The first number will be long flashes (.6 second), and the second will be short flashes (.3 second). If there is more than one MIL DTC stored, there will be a 2.1 second pause between codes.
For example, 3 long (.6 second) flashes, a pause (.9 second), then followed by 3 short (.3 second) flashes of MIL indicate a MIL Code 0303. If 2 different MIL Codes are stored, such as 0406 and 0608, this would be displayed by 4 long flashes, pause, 6 short flashes, long pause, 6 long flashes, pause, 8 short flashes of MIL.
Erasing Stored Information
Note. Test modes cannot be switched with engine running. When ignition is turned off, power to PCM will turn off after 5 seconds. PCM will then return to Diagnostic Test Mode I. Ensure test mode selector is in fully counterclockwise position when vehicle is in use.
The following emission related information will be erased from PCM memory: DTCs stored, 1st trip DTCs, freeze frame data, 1st trip freeze frame data, System Readiness Test (SRT) codes and test values. To erase this information, switch from Diagnostic Test Mode II to Diagnostic Test Mode I. While PCM is in Diagnostic Test Mode II, turn mode selector on PCM fully clockwise, wait 2 seconds and turn mode selector fully counterclockwise.
Mode 2: Freeze Frame Data
This mode gains access to emission-related data value information stored by PCM during the freeze frame portion of self-diagnostic mode during engine operation and may or may not store a Diagnostic Trouble Code (DTC). In this mode, MIL should be off, unless a DTC is present.
Mode 4: Clearing Codes
This mode can clear all emission related diagnostic information for DTCs. These include
- Clear number of DTCs (Mode 1).
- Clear DTCs (Mode 3).
- Clear freeze-frame data (Mode 2).
- Reset status of system monitoring test (Mode 1).
- Clear on board monitoring results (Mode 6 and 7).
Mode 6: On-Board Tests
This mode accesses the results of on board diagnostic monitoring tests of specific components and systems that are not continuously monitored.
Mode 7: On-Board Tests
This mode enables the on board test drive to obtain test results for emission-related powertrain components and systems that are continuously monitored during normal driving conditions.
FAIL-SAFE MODES
PCM enters a fail-safe mode if certain malfunctions are detected due to an open or short circuit. When PCM enters fail-safe mode, MIL illuminates. Refer to all diagnostic tests that apply for description and testing of circuit affected.
ECM (DTCs Not Accessible)
Maximum engine speed is 3000 RPM. Fuel injection operates in simultaneous mode. Ignition timing is fixed. Fuel pump relay remains on when engine is running and off when engine stalls. IACV-AAC valve is fully open. Cooling fans remain on at high speed when engine is running and turn off when engine stalls (if equipped).
CLEARING CODES
Note. If battery is disconnected for a prolonged period of time, all diagnostic information is cleared.
Using MIL
Turn ignition off. Wait 5 seconds. Turn ignition on. Perform MIL diagnostics for stored DTCs. See RETRIEVING CODES USING MIL . Change Diagnostic Test Mode selector switch on PCM from mode II to mode I.
FUEL FEEDBACK MONITORING USING MIL
- Enter Mode II diagnostics using MIL. See «RETRIEVING CODES USING MIL»(ref-91138-S31778384192001030200000) under SELF-DIAGNOSTIC SYSTEM. If engine is started at this stage, MIL will display condition of air/fuel mixture, monitored by the front Heated Oxygen Sensors (HO2S), whether the vehicle is in closed loop or open loop. With engine at normal operating temperature, run engine at about 2000 RPM for 2 minutes under no-load condition. MIL should flash 5 times every 10 seconds indicating normal operating condition of air/fuel mixture monitored by front HO2S(s).
- When MIL is on, it indicates a lean condition. When MIL is off, it indicates a rich condition. MIL switching on and off indicates closed loop operation. If MIL remains on or off, it indicates an open loop condition.
- To switch to opposing HO2S, turn Diagnostic Test Mode selector on PCM fully clockwise, wait 2 seconds and turn mode selector fully counterclockwise. MIL will now indicate changing to opposing HO2S by rapidly flashing and returning to lean/rich cycling. HO2S feedback of the opposing bank HO2S will now be displayed by MIL.
- Repeat step 3 to switch back to original HO2S feedback signal. Switch from bank to bank as necessary. To erase stored DTC information, go to «ERASING STORED INFORMATION»(ref-91138-S14094158572001030200000) under SELF-DIAGNOSTIC SYSTEM. To remain in Mode II, turn engine off and immediately turn ignition on.
Checking SRT Code Status
With scan tool connected, choose SRT STATUS mode (with Nissan CONSULT scan tool), or MODE 1 (OBD-II) if using a generic scan tool. On Nissan CONSULT, select DTC CONFIRMATION and check SRT STATUS. On OBD-II scan tools, follow manufacturers instructions for accessing SRT STATUS. An INCMP display for any SRT system indicates the self-diagnosis for that circuit is incomplete. SRT systems that have passed self-diagnosis will be indicated by CMPLT, indicating SRT is set. If any category is incomplete, follow SETTING SRT CODES procedure to set all SRT codes.
Setting SRT Codes
To set all SRT codes as complete, self diagnosis for the items specified must be performed one or more times. See appropriate SYSTEM READINESS TEST (SRT) CODE IDENTIFICATION table. With scan tool connected to Data Link Connector (DLC), start engine and allow vehicle to warm to operating temperature and coolant temperature greater than 158°F (70°C). Drive vehicle according to procedure shown in illustration. (Scheme 2) Perform driving procedure one or more times. If driving procedure is interrupted, repeat procedure. On A/T models, operate vehicle with shift lever in "D" position and overdrive ON. On M/T models, shift gears at suggested speeds. See M/T SHIFT POINTS table.
Scheme 2
| Application | Shift Speed MPH | ||
|---|---|---|---|
| Altima | |||
| Cruising Below 4000 Ft. Elevation | |||
| 1-2 | 15 | ||
| 2-3 | 18 | ||
| 3-4 | 30 | ||
| 4-5 | 39 | ||
| Acceleration Below 4000 Ft. Elevation | |||
| 1-2 | 15 | ||
| 2-3 | 25 | ||
| 3-4 | 36 | ||
| 4-5 | 40 | ||
| Quick Acceleration | |||
| 1-2 | 15 | ||
| 2-3 | 25 | ||
| 3-4 | 40 | ||
| 4-5 | 45 | ||
| Frontier 4-Cylinder | |||
| 1-2 | 15 | ||
| 2-3 | 25 | ||
| 3-4 | 40 | ||
| 4-5 | 45 | ||
| Frontier V6, Pathfinder & QX4 | |||
| Cruising Below 4000 Ft. Elevation | |||
| 1-2 | 15 | ||
| 2-3 | 18 | ||
| 3-4 | 30 | ||
| 4-5 | 39 | ||
| Acceleration Below 4000 Ft. Elevation | |||
| 1-2 | 15 | ||
| 2-3 | 25 | ||
| 3-4 | 36 | ||
| 4-5 | 40 | ||
| Quick Acceleration | |||
| 1-2 | 15 | ||
| 2-3 | 25 | ||
| 3-4 | 40 | ||
| 4-5 | 45 | ||
| Maxima | |||
| Cruising Below 4000 Ft. Elevation | |||
| 1-2 | 13 | ||
| 2-3 | 16 | ||
| 3-4 | 27 | ||
| 4-5 | 36 | ||
| Acceleration Below 4000 Ft. Elevation | |||
| 1-2 | 13 | ||
| 2-3 | 23 | ||
| 3-4 | 33 | ||
| 4-5 | 39 | ||
| Quick Acceleration | |||
| 1-2 | 15 | ||
| 2-3 | 25 | ||
| 3-4 | 40 | ||
| 4-5 | 45 | ||
| Sentra | |||
| 1-2 | 15 | ||
| 2-3 | 25 | ||
| 3-4 | 40 | ||
| 4-5 | 45 | ||
M/T SHIFT POINTS
| Category/System Monitored | DTC/ (1) MIL Code | ||
|---|---|---|---|
| Catalyst System | |||
| Three Way Catalyst | P0420/0702 | ||
| EVAP System | |||
| EVAP Control System | |||
| Small Leak - Negative Pressure | P0440/0705 | ||
| Small Leak - Positive Pressure | P1440/0213 | ||
| Purge Flow | P01447/0111 | ||
| HO2S Sensor | |||
| Front HO2S | |||
| Circuit | P0130/0303 | ||
| Lean Shift | P0131/0411 | ||
| Rich Shift | P0132/0410 | ||
| Response | P0133/0409 | ||
| High Voltage | P0134/0412 | ||
| Rear HO2S | |||
| Minimum Voltage | P0137/0511 | ||
| Maximum Voltage | P0138/0510 | ||
| Response | P0139/0707 | ||
| High Voltage | P0140/0512 | ||
| HO2S Sensor Heater System | |||
| Front | P0135/0901 | ||
| Rear | P0141/0902 | ||
| EGR System | |||
| EGR Function | |||
| Closed | P0400/0302 | ||
| Open | P1402/0514 | ||
| EGRC-BPT Valve Function | P0402/0306 | ||
| (1) Malfunction Indicator Light (MIL) fault codes. See ENTERING SELF-DIAGNOSTICS. | |||
| (1) | Malfunction Indicator Light (MIL) fault codes. See ENTERING SELF-DIAGNOSTICS. |
SYSTEM READINESS TEST (SRT) CODE IDENTIFICATION (ALTIMA, FRONTIER 4-CYL., QUEST & SENTRA)
| Category/System Monitored | DTC/ (1) MIL Code | ||
|---|---|---|---|
| Catalyst System | |||
| Three Way Catalyst | |||
| Right Bank | P0420/0702 | ||
| Left Bank | P0430/0703 | ||
| EVAP System | |||
| EVAP Control System | |||
| Small Leak - Negative Pressure | P0440/0705 | ||
| Small Leak - Positive Pressure | P1440/0213 | ||
| Purge Flow | P1447/0111 | ||
| HO2S Sensor | |||
| Front HO2S | |||
| Circuit | P0130/0503 & P0150/0303 | ||
| Lean Shift | P0131/0411 & P0151/0415 | ||
| Rich Shift | P0132/0410 & P0152/0414 | ||
| Response | P0133/0409 & P0153/0413 | ||
| High Voltage | P0134/0412 & P0154/0509 | ||
| Rear HO2S | |||
| Minimum Voltage | P0137/0511 | ||
| Maximum Voltage | P0138/0510 | ||
| Response | P0139/0707 | ||
| High Voltage | P0140/0512 & P0160/0315 | ||
| HO2S Sensor Heater System | |||
| Front | P0135/0901 & P0155/1001 | ||
| Rear | P0141/0902 & P0161/1002 | ||
| EGR System | |||
| EGR Function | |||
| Closed | P0400/0302 | ||
| Open | P1402/0514 | ||
| EGRC-BPT Valve Function (2) | P0402/0306 | ||
| (1) Malfunction Indicator Light (MIL) fault codes. See ENTERING SELF-DIAGNOSTICS. (2) Except Maxima. | |||
| (1) | Malfunction Indicator Light (MIL) fault codes. See ENTERING SELF-DIAGNOSTICS. |
| (2) | Except Maxima. |
SYSTEM READINESS TEST (SRT) CODE IDENTIFICATION (FRONTIER V6, MAXIMA, PATHFINDER & QX4)
FINAL CHECK FOR ALL CODE CHARTS
Unless otherwise instructed, perform following FINAL CHECK after each repair is completed.
- Perform DTC CONFIRMATION TEST at beginning of diagnostic test.
- Clear all DTCs stored in PCM memory. See «CLEARING CODES»(ref-91138-S19289434172001030200000) under SELF-DIAGNOSTIC SYSTEM.
- Ensure pass code is displayed on scan tool, or by MIL in mode II.
- Perform a test drive.
- Verify no DTCs are present in PCM memory. If results are okay, inspection is complete. If results are not okay, repeat circuit test for remaining DTC(s).
Ensure PCM pin terminals and harness connector are not damaged.
SUMMARY
If no DTCs (or only pass codes) are present and driveability symptoms exist, or intermittent codes exist, proceed to TROUBLE SHOOTING - NO CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.) or intermittent diagnostic procedures.