Diagnosis & Repair Procedure
- Perform DTC CONFIRMATION TEST . If DTC P0131 or P0132 is set, go to next step. If DTCs P0131 and P0132 are not set, problem is intermittent. System is okay at this time. See TROUBLE SHOOTING - NO CODES article.
- Turn ignition off. Connect scan tool. Start engine and allow it to reach normal operating temperature. Increase and hold engine speed at 2000 RPM for one minute. Allow engine to return to idle. Rapidly increase engine speed 5-6 times repeatedly while monitoring HO2S B1 S1 parameter on scan tool. If reading does not vary from less than 0.3 volt to more than 0.6 volt, go to next step. If reading varies from less than 0.3 volt to more than 0.6 volt, go to step 5.
- Turn ignition off. Disconnect HO2S B1 S1 connector. Check for poor terminal contact at HO2S B1 S1 connector. If poor terminal contact is found, repair as necessary and go to DTC CONFIRMATION TEST . If terminal contact is okay, start engine. Measure voltage between HO2S B1 S1 connector terminals No. 1 (Gray/Yellow wire) and No. 2 (Red wire) while repeatedly revving engine. If reading varies from less than 0.3 volt to more than 0.6 volt, go to next step. If reading does not vary from less than 0.3 volt to more than 0.6 volt, replace HO2S B1 S1 and retest system.
- Check for short or open in Red wire between HO2S B1 S1 and PCM 26-pin connector C51-3 terminal No. 11. Also check for short or open in Gray/Yellow wire between HO2S B1 S1 and PCM 26-pin connector C51-3 terminal No. 25. See WIRING DIAGRAMS article. Repair as necessary. If wires are okay, replace PCM and go to DTC CONFIRMATION TEST
- Operate engine at 2000 RPM for one minute. Reduce engine speed. With engine idling, using scan tool, check short term fuel trim value. If value is between -20 and +20 percent, problem is intermittent. System is okay at this time. See TROUBLE SHOOTING - NO CODES article. Go to next step.
- If intermittent problem is not found, replace PCM and go to DTC CONFIRMATION TEST . If value is not between -20 and +20 percent, go to DTC P0171: TOTAL LEFT BANK FUEL TRIM IS GREATER THAN ALLOWED SPECIFICATION, OR DTC P0172: TOTAL LEFT BANK FUEL TRIM IS LESS THAN ALLOWED SPECIFICATION .