Conditions for Running the DTC

WARNING: This page is about a different car, the 2004 Buick Rendezvous. However, it is still accessible from the selected car via links, so may be relevant.

Conditions 1

Before the ECM can report DTC P2237 failed, DTCs P0101, P0121, P0122, P0123, P0221, P0222, P0223, P0335, P0336, and P0338 must run and pass.
DTCs P0030, P0031, P0032 are not set.
The ignition 1 voltage is between 10.7-18 volts
The engine is operating in closed loop.
The HO2S heater is at operating temperature.
The ECM is commanding the lambda more than 1.03 or less than 0.97.
DTC P2237 runs continuously once the above conditions are met.

Conditions 2

Before the ECM can report DTC P2237 failed, DTCs P0101, P0121, P0122, P0123, P0221, P0222, P0223, P0335, P0336, and P0338 must run and pass.
The ignition 1 voltage is between 10.7-18 volts
The engine is operating in closed loop.
The HO2S heater is at operating temperature.
The ECM detects the internal HO2S signal voltage is between 1.48-1.52 volts.
The ECM is commanding the lambda rich and then lean periodically with a change of more than 2 percent.
DTC P2237 runs continuously once the above conditions are met.

Conditions 3

Before the ECM can report DTC P2237 failed, DTCs P0101, P0121, P0122, P0123, P0221, P0222, P0223, P0335, P0336, and P0338 must run and pass.
DTCs P0030, P0031, P0032 are not set.
The ignition 1 voltage is between 10.7-18 volts
The HO2S heater is at operating temperature.
DTC P0133 ran and completed.
DTC P2237 runs continuously once the above conditions are met.