Jeep Grand Cherokee 1999 — technical service bulletin
Bulletin 181599 · NHTSA communication 606167 · issued Jun 18, 1999
Technical service bulletin
communication type
Engine and Engine Cooling
component
1999
model years
1
vehicle entries
Official summary
Several revisions have been made to the idle strategy of the 4.7l engine. One change is to the upstream oxygen sensor (o2) biasing / switching when the transmission is in park or neutral. *tt
Vehicles covered
What a TSB means. Technical service bulletins are repair guidance manufacturers send to dealers — they are not recalls, and repairs are not automatically free (warranty extensions are an exception worth checking). The full document is available via NHTSA’s vehicle lookup.