Diagnostic Aids

DTC P1133 is most likely caused by one of the following conditions:

• The fuel pressure. The system will go rich if fuel pressure is too high. The PCM can compensate for some increase. If the fuel pressure gets too high, a DTC P0172 will be set. See appropriate BASIC DIAGNOSTIC PROCEDURES article.
• A leaking injector. A leaking or malfunctioning injector can cause the system to go rich.
• The manifold absolute pressure (MAP) sensor. An output that causes the PCM to sense a higher than normal manifold pressure, indicating a low vacuum, can cause the system to go rich. Disconnecting the MAP sensor will allow the PCM to set a fixed value for the MAP sensor. Substitute a different MAP sensor if the rich condition is gone while the sensor is disconnected.
• The pressure regulator. Check for a leaking fuel pressure regulator diaphragm by checking for the presence of liquid fuel in the vacuum line to the regulator.
• The Throttle Position (TP) sensor. An intermittent TP sensor output will cause the system to go rich due to a false indication of the engine accelerating.
• HO2S 1 contamination. Inspect HO2S 1 for Silicone contamination from fuel or from the use of an incorrect RTV sealant. The sensor may have a white powdery coating. This condition can result in a high but false voltage signal, indicating a rich exhaust. The PCM will then reduce the amount of fuel delivered to the engine, causing a severe surge or driveability problem.