Oxygen Sensor - Operating Differences

NO: 18-31-98

GROUP: Vehicle Performance

DATE: Sep. 25, 1998

SUBJECT:
Oxygen Sensor (02)
Operating Differences

MODELS:

1999 (WJ) Grand Cherokee

NOTE:
THIS INFORMATION APPLIES TO VEHICLES EQUIPPED WITH A 4.7L ENGINE.

DISCUSSION:

To enhance the idle quality of the 4.7L engine, the 02 sensor will be biased rich when the engine is at idle and the transmission is in Park or Neutral. The upstream goal voltage during this time will be between 0.7 and 0.85 volts. The 02 sensor should not be condemned for slow or no switching while at idle and in Park or Neutral.

02 switching tests should be performed off idle in any gear, or at idle in a forward gear range. During these conditions, the 02 sensor goal voltage will be in the normal (0.5 volt) range.

POLICY: Information Only