Diagnostic Aids

DTC P1133 is most likely caused by one of following items:

• Fuel Pressure - The system will go rich if fuel pressure is too high. The PCM/ECM can compensate for some increase. However, if it gets too high. a DTC P1133 may set. Refer to "Fuel System Diagnosis".
• Leaking Injector - A leaking or malfunctioning injector can cause system to go rich.
• Manifold Absolute Pressure (MAP) Sensor - An output that causes PCM/ECM to sense a higher than normal manifold pressure (low vacuum) can cause system to go rich. Disconnecting MAP sensor will allow PCM/ECM to set a fixed value for MAP sensor. Substitute a different MAP sensor if rich condition is gone while sensor is disconnected.
• Pressure Regulator - Check for a leaking fuel pressure regulator diaphragm by checking for presence of liquid fuel in vacuum line to pressure regulator.
• Throttle Position (TP) Sensor - An intermittent TP sensor output can cause system to go rich due to a false indication of engine accelerating.
• O2S1 Contamination - Inspect O2S1 for silicone contamination from fuel or improper use of RTV sealant. The sensor may have a white powdery coating and result in a high but false voltage signal (rich exhaust indication). The PCM/ECM will then reduce amount of fuel delivered to engine causing a severe surge or driveability problem.