Engine - Intermittent Roughness/MIL ON/Codes Set

91chevy18

Number: 91-353-6E

Section: 6E

Date: JUNE 1991

Corporate Bulletin No.: 136513


Subject: INTERMITTENT ENGINE ROUGHNESS, CEL CODE 13 AND 44


Model and Year: 1988-91 S TRUCKS WITH 2.5L ENGINE


Condition: A customer may comment of an engine roughness or CEL (check engine light) with a stored code of either 13 (02 sensor failure) or 44 (02 sensor lean). This could be an intermittent condition.





Cause: The cause is an abrasion of the insulation on the oxygen sensor wire in the engine wiring harness between the plastic conduit and the connector to the oxygen sensor. This abrasion occurs when the wire is not properly secure in place. The wire is allowed to rest against either the fuel filter or the rear most head bolt stud (See Illustration). Over time, the wire will abrade through the insulation and short out on either the fuel filter or the head bolt.

Correction: Any time that a problem with the oxygen sensor is suspect the wiring harness should be inspected for any signs of abrasion. If any evidence of abrasion is found, the wiring should be repaired and secured to the fuel return line in such a way that the abrasion can no longer occur.


Use applicable labor operation and time.