Hard Failures
To prevent a false DTC from being stored in PCM memory, a malfunction must be detected during 2 consecutive drive cycles. This applies to HO2S sensors, fuel metering-related components, idle control system, ECT sensor, EGR system, Three-Way Catalytic Converter (TWC) system, EVAP control system and other self-diagnostic functions. The first occurrence of a detected malfunction is stored in PCM memory. If the same malfunction is detected again after the ignition switch is turned off and then back on, a hard failure DTC is stored and the MIL is turned on. Malfunction Indicator Light (MIL) will remain on until detected malfunction is repaired. Malfunction can be determined by retrieving DTCs. See DIAGNOSTIC TROUBLE CODE IDENTIFICATION . See RETRIEVING CODES .
Fail-Safe Function
If a sensor fails, PCM will substitute a preprogrammed value for the sensor and continue engine operation. In this condition, engine will operate, but driveability will not be optimum.
Back-Up Function
When a malfunction is detected in PCM, fuel injection is controlled by an independent back-up system, permitting minimal driving.
Intermittent Failures
An intermittent failure means that a system may have had a malfunction, but is okay now. Intermittent failures may cause Malfunction Indicator Light (MIL) to flicker or illuminate and go out after the intermittent fault goes away. The corresponding DTC will be retained in Powertrain Control Module (PCM) memory. Intermittent failures may be caused by sensor, connector or wiring-related problems. See INTERMITTENTS in TESTS W/O CODES article.
MALFUNCTION INDICATOR LIGHT
All models are equipped with a Malfunction Indicator Light (MIL). As a bulb check, light illuminates for about 2 seconds when ignition switch is turned to ON position and engine is not running. MIL also illuminates when a system failure has been detected and a corresponding DTC has been set in Powertrain Control Module (PCM) memory. Not all trouble codes will activate MIL. If MIL is on and no DTCs are in memory, problem may be intermittent. See INTERMITTENTS in TESTS W/O CODES article.
RETRIEVING CODES
Note. Self-diagnostics are limited when accessing codes using MIL. For complete self-diagnostic capabilities, an OBD-II compliant scan tool or Honda PGM Tester is required.
Malfunction Indicator Light (MIL)
Codes can also be accessed by using MIL. Turn ignition switch to OFF position. On Accord, connect SCS Service Connector DLC (07WAZ-002010A ) to 16-pin Data Link Connector (DLC) located under instrument panel, near driver-side kick panel. On all models except Accord, connect SCS Service Connector (07PAZ-0010100 ) to 2-pin service check connector. On Civic, service check connector is located under passenger-side of instrument panel. (Scheme 19) On CR-V, Oasis and Odyssey, service check connector is located under passenger-side of instrument panel behind center console. On Prelude, service check connector is located behind access cover on right side of center console.
On all models, turn ignition switch to ON position. Diagnostic Trouble Codes (DTCs) will be indicated by a series of long and short flashes on MIL. The number of long flashes indicate the number in the tens column. The number of short flashes indicate the number in the ones column. For example, 4 long flashes followed by 3 short flashes would indicate DTC 43. See DIAGNOSTIC TROUBLE CODE IDENTIFICATION below and/or proceed to DIAGNOSTIC TROUBLE CODE IDENTIFICATION and CIRCUIT TESTS in appropriate TESTS W/CODES article.
Scheme 19
FREEZE FRAME DATA
Freeze frame data indicates engine operating conditions when the first malfunction, misfire or fuel trim malfunction was detected. Freeze frame data is read using a Honda PGM tester or OBD-II scan tool. Follow manufacturer's instructions.
SUMMARY
If the MIL does not illuminate, indicating a Diagnostic Trouble Code (DTC) has been set and there is a driveability malfunction, go to TESTS W/O CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.) or intermittent diagnostic procedures. Some troubleshooting steps may require resetting PCM and attempting to duplicate DTC. If malfunction is intermittent and DTC cannot be duplicated, discontinue troubleshooting procedures and go to TESTS W/O CODES article for diagnosis by symptom. If DTC cannot be duplicated, continuing with troubleshooting procedures will cause confusion and could result in unnecessary component replacement.