E045

TEST CONDITIONS
1. Codes EO14, EO15, EO16, EO21, EO22, EO26, EO27, EO31, EO32, and EO34 not set;
2. Low battery condition does not exist;
3. Throttle switch open;
4. TPS equal to or greater than 6°;
5. TPS less than or equal to 30°;
6. Coolant temp equal to or greater than 58°C;
7. Left oxygen sensor ready;
8. RPM equal to or greater than 800;
9. TPS less than or equal to 10° and canister purge has purged at full duty cycle for 5 minutes since the engine was running with coolant equal to or greater than 80°C.

FAILURE CONDITIONS
Right oxygen sensor remains rich for more than 50 seconds.

ACTION TAKEN
1. ECM turns on "Engine Control System Fault" telltale;
2. ECM commands BCM to display "Service Now" message on Driver Information Center (DIC);
3. ECM enables canister purge;
4. ECM disables AIR management solenoid;
5. ECM uses left oxygen sensor information for fuel control unless codes EO17, EO42, or EO43 are set.

DESCRIPTION
The ECM provides a 0.45 volt reference signal to the oxygen sensor on CKT 412. When the oxygen sensor is cold (below 200°C), the oxygen sensor signal voltage will be around 0.45 volts and the ECM will keep the system is open loop operation. When the oxygen sensor is warm (above 200°C), the oxygen sensor will swing from rich to lean rapidly, at least one swing every two seconds, if the ECM is in good control of the air fuel mixture.

When the ECM sees that the oxygen is varying from the cold voltage of 0.45 volt, it will send the system into closed loop operation. In closed loop operation, the ECM will adjust the fuel delivery rate to the engine based on the oxygen sensor readings.

Code EO45 is designed so that if the oxygen sensor stays at a rich voltage for more than 50 seconds during the test conditions, Code EO45 will set.

Code EO45 will set when:
1. There is an oxygen sensor circuit fault giving a false rich indication
or
2. When the air fuel ratio is actually lean due to a fuel control or emission system fault.

Notes on Fault Tree
1. With the oxygen sensor disconnected, parameter ED33 should remain at reference voltage (0.38 to 0.63 volts).
2. Checking for sensor circuitry able to record lean readings.
3. The ECM compares oxygen sensor signal voltage received on circuit 412 to the ground voltage on circuit 413. If the ground voltage on circuit 413 is not engine ground (battery negative), the oxygen sensor can appear falsely high or low. With the engine running, use a voltmeter to measure voltage from the oxygen sensor pin A to the ECM terminal E15. If the voltage is greater than -0.05 to +0.05 volts, repair poor ground on CKT 413 between ECM terminal E15 and engine ground.

Notes on Intermittents
Engine running, manipulate the oxygen sensor and ECM wiring and connectors while observing ECM Data ED33. If the fault is induced, ED33 will jump above 0.63 volts and the "ECON" status light will go on. Manipulate CKT 413 ground to the engine and look for a loose ground eyelet or ground eyelet installed at wrong location. Check oxygen sensor connector terminals for signs of corrosion or foreign material. Clean if signs of corrosion are evident. If rich engine operation is suspected, perform "PFI System Check". See Symptoms - "Poor Fuel Economy" and "Excessive Exhaust Emissions". Testing and Inspection

If the oxygen sensor circuit appears to be OK, go to PFI Chart A-9, "Oxygen Sensor Diagnosis" to check for faulty or contaminated sensor. Related Tests, Information and Procedures