E045

ECM Code E045:

Oxygen Sensor Circuit:

DESCRIPTION:

The ECM provides a .45 volt reference signal to the oxygen sensor on CKT 412. When the oxygen sensor is cold (below 200°C), the output voltage will be around 0.45 volts, and the ECM will keep the system in open loop operation. When warm, a properly operating oxygen sensor will drive the .45 volt reference lower (below .45 volts) to indicate a lean mixture and higher (above .45 volts) to indicate a rich mixture. The oxygen sensor signal voltage 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 sensor is not at the cold voltage of 0.45 volts, it will send the system into closed loop operation. In closed loop operation, the ECM will meter fuel into the engine based on the oxygen sensor readings. Code E045 is designed so that if the oxygen sensor stays at a rich voltage for more than 45 seconds during the test conditions, code E045 will set.

Code E045 can be caused by:

1. Oxygen sensor circuit faults.
2. Air fuel ratio actually rich due to a fuel control or emissions system fault.

TEST CONDITIONS:

1. Codes EO14, EO15, EO16, E021, E022, E026, E027, E031, E032, and E034 all must be clear.
2. Throttle switch open.
3. TPS between 6 and 29 degrees and steady.
4. Coolant sensor greater than or equal to 80°C.
5. Oxygen sensor ready (closed loop).
6. Not accelerating or decelerating.
7. Engine speed greater than or equal to 800 RPM.
8. Vehicle operated at above 13 degrees TPS for 10 minutes.
9. Canister purge enabled.

FAILURE CONDITIONS:

Oxygen sensor stays rich for more than 45 seconds.

ACTION TAKEN:

1. ECM turns on "SERVICE ENGINE SOON" telltale.
2. ECM commands BCM to display "SERVICE CAR SOON" message on CCDIC.
3. ECM turn on canister purge solenoid and turns off air management solenoids.
3. ECM switches to open loop operation.

NOTES ON FAULT TREE:

1. With the oxygen sensor disconnected, parameter ED07 should remain at reference voltage (.38 to .63 volts)

2. Checking for ECM's ability to recognize lean input on oxygen sensor signal CKT 412.

3. The ECM compares oxygen sensor signal voltage received on circuit 412 to the ground voltage on circuit 413. If the ECM doesn't have a good ground to the engine on circuit 413, the oxygen sensor can appear falsely high or low. With engine running, use a voltmeter to measure voltage from the oxygen sensor at the exhaust manifold to the ECM terminal A1. If the voltage is -.05 volts to +.05 volts then the ground is OK. If the voltage is less than -.05 volts or greater than +.05 volts, repair poor ground on CKT 413 between ECM terminal A1 and the ground at front of engine, right (rearmost) head.

NOTE ON INTERMITTENTS:

Engine running, manipulate the oxygen sensor and ECM wiring and connectors while observing ECM parameter ED07. If the fault is induced, ED07 will jump above .63 volts, "ECON" status light will come on. Manipulate CKT 413 ground to the engine and look for a loose ground eyelet or ground eyelet installed in an improper location.

Perform DFI SYSTEM CHECK under "A" CHARTS. See DIAGNOSIS BY SYPMTOMS - "Poor Fuel Economy" and "Excessive Exhaust Emissions, Odors". If the oxygen sensor circuit appears to be OK, go to OXYGEN SENSOR CIRCUIT CHECK under "C" CHARTS, to check for a faulty or contaminated sensor.

Review the snapshot data parameters stored with this code to verify failure condition. If the failure condition is verified, check and repair intermittent wiring connection, or sensor.