E013

Code E13:

Oxygen Sensor Circuit:

DESCRIPTION:

The PCM/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 PCM/ECM assumes that the sensor can't respond to air/fuel mixtures rich or lean and code E13 is set. Possible causes of code E13 are:
1. An open in CKT 412 or 413.
2. A short to voltage on CKT 412 or 413.
3. An oxygen sensor that cannot respond.

TEST CONDITIONS:

1. Codes E14, E15, E21, E22, E26, and E27 not set.
2. Coolant temperature greater than or equal to 58°C.
3. TPS value between 6 and 30 degrees.
4. Throttle switch open.
5. Engine speed greater than or equal to 800 RPM.

FAILURE CONDITIONS:

Oxygen sensor voltage stays between .609 volts and .307 volts for more than 40 seconds (oxygen sensor voltage not toggling).

ACTION TAKEN:

1. PCM/ECM turns on "SERVICE ENGINE SOON" telltale.
2. Closed Loop is disabled.

NOTES ON FAULT TREE:

1. At key on with oxygen sensor disconnected, the parameter P.0.7 should read about .45 volts. Lower or higher voltage indicates circuit problems.

2. The PCM/ECM compares voltage on CKT 412 to the ground voltage on CKT 413. It is essential that the oxygen sensor ground and the PCM/ECM ground on pin E15 are at the same voltage potential with engine running.

NOTE ON INTERMITTENTS:

If code E13 is a history code, start engine and enter diagnostics. Operate engine at fast idle until "Auto" closed loop status light is turned on. Observe parameter P.1.4 while manipulating CKT's 412 and 413 wiring. If parameter P.1.4 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 rear most cylinder head.