SES Light Due to a P0171 DTC - Reprogram PCM - keywords calibration CEL clean controls ECM engine fuel gas injector lean repeat restricted

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Under certain driving conditions, a SES Light may be experienced due to a P0171 DTC.

If the SI diagnostics do not isolate a cause for the P0171, reprogram the PCM with the latest TIS2000 calibrations. PCM calibrations are now available that may address certain P0171 DTCs.

For 2004 model year vehicles, the updated TIS2000 calibration for P0171 DTCs is titled - "Calibration to address coast down idle roughness and revise cruise control operation with less vehicle speed deviation. Also contains diagnostic enhancements for DTC P0171". This calibration was released in TIS2000 Version 2.0, which became available to dealers on 2/7/2005.

For 2005 model year vehicles, the updated TIS2000 calibration for P0171 DTCs is titled - "New calibration to ensure proper catalyst monitoring at idle". This calibration was released in TIS2000 Version 5.5, which became available to dealers on 5/16/2005.

The above calibrations, or any that follow, are designed to address certain P0171 DTCs.

If the updated PCM calibrations do not repair a P0171 and the SI diagnostics do not isolate a cause for the DTC, clean the fuel injectors by following bulletin 03-06-04-030A. If this repairs the P0171, use of a top tier filling station should be encouraged to prevent a possible reoccurrence. Please review 04-06-04-047D for more information on top tier filling stations. If a top tier filling station is not used, maintenance cleaning of the fuel injectors may be necessary to prevent a reoccurrence. Please review 04-06-04-051A for more details on maintenance cleaning of the fuel injectors.

Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.