E013

ECM Code E013:

Oxygen Sensor Circuit:

DESCRIPTION:

The ECM provides a .45 volt reference to the oxygen sensor on CKT 412. When warm, a properly operating oxygen sensor will drive the .45 volt reference lower (below .45 volts) to indicate lean mixtures and higher (above .45 volts) to indicate a rich mixture. If under the above test conditions the oxygen sensor doesn't vary from the "cold" or "not ready" voltage, the ECM assumes that the sensor can't respond to air/fuel mixtures rich or lean and code E013 is set.

If code EO13 is accompanied by current or history code E045, use the code E045 fault tree to diagnose. If code EO13 is accompanied by current or history code E044, use the code E044 fault tree to diagnose.

TEST CONDITIONS:

1. Codes EO14, EO15, E021, E022, E026, E027 clear.
2. Coolant temperature greater than or equal to 80°C.
3. TPS value between 6 and 29 degrees.
4. Throttle switch open.
5. Engine speed greater than or equal to 800 RPM.

FAILURE CONDITIONS:

Oxygen sensor voltage stays between .275 volts and .630 volts for more than 30 seconds (oxygen sensor voltage not toggling).

ACTION TAKEN:

1. ECM turns on "SERVICE ENGINE SOON" telltale.
2. ECM commands BCM to display "SERVICE SOON" message on CCDIC.
3. ECM turns on canister purge, diverts AIR system to air cleaner.
4. Closed Loop is disabled.

NOTES ON FAULT TREE:

1. At key on with oxygen sensor disconnected, the parameter ED07 should read about .45 volts. Lower or higher voltage indicates circuit problems.

2. The ECM compares voltage on CKT 412 to the ground voltage on CKT 413. It is essential that the oxygen sensor ground and the ECM ground on pin A1 show good continuity (no voltage difference) with engine running.

3. Fault is most likely at ECM connector or the ECM. Before replacing the ECM, perform the "ECM Replacement Check", Chart C-1.

NOTE ON INTERMITTENTS:

If code EO13 is a history code, start engine, enter diagnostics. Operate engine at fast idle until "Auto" closed loop status light is turned on. Observe parameter ED07 while manipulating CKT's 412 and 413 wiring. If parameter ED07 changes from fluctuating to fixed at about .45 volts, repair intermittent open circuit. Check CKT 413 ground to engine for proper installation (clean, tight, star washer installed). Ground for CKT 413 is attached to the front of the engine at the right or rearmost cylinder head. 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.