DTC P0133 Or P0153 - Fuel Control: Condition

This code indicates that response rate is below calibration in HO2S. Possible causes are as follows:

• Open or shorted circuit.
• Exhaust leak.
• Excessive fueling.
• HO2S coated with contaminants.
• Faulty MAF sensor.
• Leak in air induction system.

1) Perform KOER Self-Test  If DTC P1127 or P1128 is present, service before proceeding. If DTC P1127 or P1128 is not present, go to next step.

2) HO2S Response Test  With scan tool connected, turn ignition on. Access Generic OBD-II functions and enter. Select Diagnostic Monitoring Test Results and enter. Scroll to Test ID: 01 and enter. Press Start. If measured value is 614 or more, fault cannot be duplicated or identified at this time and testing is complete. If measurement fault is less than 614, go to next step.

3) Check For HO2S Contamination  Check following possibilities as potential source of contamination:

• Use of unapproved silicone sealers.
• Use of unapproved cleaners.
• Fuel contaminated by silicone additives.
• Fuel contaminated by lead.
• Excessive oil burning.
• Antifreeze leaking internally.

If any of these conditions are present, repair or replace as necessary. Replace HO2S. Change oil, filter and repeat QUICK TEST. If none of these conditions are present, go to next step.

4) Check For Unmetered Air Leaks  Vacuum or air leaks in non-EEC-V areas could cause fault code to set. Check the following as potential source of air leak:

• Leaking vacuum hoses.
• Leaking intake manifold gasket.
• EGR system.
• PCV system.
• Poorly seated oil dipstick and/or dipstick tube.

If any of these conditions are present, repair or replace as necessary. Perform drive cycle and repeat QUICK TEST. If none of these conditions are present, go to next step.

5) Check HO2S Circuits  Turn ignition off. Disconnect PCM and suspect HO2S wiring harness connector. Inspect connectors for damage and repair as necessary. Connect jumper wire between HO2S SIG and VPWR at sensor wiring harness connector. With scan tool connected to DLC, turn ignition on. Access HO2S PID. If PID voltage is less than 1.5 volts, go to next step. If PID voltage is 1.5 volts or more, replace HO2S and change engine oil. Test drive vehicle and repeat QUICK TEST.

6) Check HO2S Signal Circuit Resistance  Turn ignition off. Disconnect PCM 104-pin connector. Inspect connector for damage and repair if necessary. Install Breakout Box (014-00950), leaving PCM disconnected. Measure resistance between suspect HO2S test pin at breakout box and HO2S terminal at wiring harness connector. Measure resistance between SIG RTN test pin No. 60 at breakout box and SIG RTN terminal at wiring harness connector. If either resistance is 5 ohms or more, repair open circuit. Drive vehicle at 55 MPH for 5 minutes and repeat QUICK TEST. If each resistance is less than 5 ohms, go to next step.

7) Check HO2S For Short Circuit  Ensure ignition is off and PCM is disconnected. Disconnect scan tool from DLC. Measure resistance between HO2S test pin No. 60 and test pins No. 71 and 97 (VPWR) at breakout box. Measure resistance between suspect HO2S test pin and test pin No. 91 (SIG RTN) at breakout box. If either resistance is less than 10,000 ohms, repair short circuit. Drive vehicle for 5 miles at 55 MPH and repeat QUICK TEST. If each resistance is 10,000 ohms or more, replace PCM.