Code 45, Rich Exhaust Indication: Notes

The ECM supplies a voltage of about .45 volts between circuits No. 412 and 413. The O2 sensor varies the voltage from one volt (rich exhaust) to .10 volt (lean exhaust). The sensor acts like an open sensor circuit and produces no voltage when exhaust temperature is low. An open sensor circuit or cold sensor causes open loop operation.

Code 45 is set when O2 sensor signal at ECM is above .75 volts for 30 seconds and time since engine start is one minute or more. Code 45 indicates a rich exhaust and diagnosis should begin by checking for proper fuel pressure, leaking injectors, HEI shielding, canister purge saturation, coolant sensor, MAP sensor, O2 sensor contamination and TPS intermittent output.

1. Test determines if O2 sensor is registering a rich condition.