Diagnostic Aids

WARNING: This page is about a different car, the 2002 GMC Sonoma and 2002 Chevrolet S10 Pickup. However, it is still accessible from the selected car via links, so may be relevant.

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

The system will go rich if fuel pressure is too high. The PCM can compensate for some increase, however, if pressure gets too high DTC P0172 will be set.
A leaking or malfunctioning injector can cause the system to go rich.
An output that causes the PCM to sense a higher than normal manifold pressure, or 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.
Inspect for a leaking fuel pressure regulator diaphragm by inspecting for the presence of liquid fuel in the vacuum line to the regulator.
An intermittent TP sensor output will cause the system to go rich due to a false indication of the engine accelerating.
Inspect O2S 1 for silicone contamination from fuel or use of improper RTV sealant. The sensor may have a White powdery coating and result in a high but false voltage signal, a rich exhaust indication. The PCM will then reduce the amount of fuel delivered to the engine causing a severe surge or driveability problem.