Diagnostic Aids

DTC P0133 or slow response is most likely caused by one the following items:

• Fuel pressure - The system will go rich if fuel pressure is too high. The ECM can compensate for some increase, but if it gets too high, a DTC P0133 may set. Refer to "Fuel System Diagnosis".
• Leaking injector - A leaking or malfunctioning injector can cause the system to go rich.
• Manifold Absolute Pressure (MAP) sensor - An output that causes the ECM to sense a higher than normal manifold pressure (low vacuum) can cause the system to go rich. Disconnecting the MAP sensor will allow the ECM to set a fixed value for the MAP sensor. Substitute an different MAP sensor if the rich condition is gone while the sensor is disconnected.
• Throttle Position (TP) sensor - An intermittent TP sensor output can cause the system to go rich due to a false indication of the engine accelerating.
• HO2S1 contamination - Inspect HO2S1 for silicone contamination from fuel or use of improper room temperature vulcanizing (RTV) sealant. The sensor may have a white powdery coating, resulting in a high but false voltage signal (rich exhaust indication). The ECM will then reduce the amount of fuel delivered to the engine causing a severe surge or driveability problem.