Originally Posted By: demarpaint
I haven't had it happen yet with my 08 Jeep Liberty. I had an EVAP Emissions System Small leak, nothing to do with MMO though, it was a bad gas cap.
Do you have one of the Pentastar engines in your GC that might be tripping the CEL due to a bad head? I'm watching that unfold closely. I have my heart set on a 2013 Wrangler but want to be sure they have it all worked out first.
Edit to add: This might pertain to the GC and others with the 3.6 engine, it might be worth looking into.
4 oz of MMO to 10 gallons of gas isn't going to trip a CEL. Call Turtle Wax and ask.
TSB 18-054-11 released 12/15 for a pcm update, your codes not included, but ought to be done regardless. Save some future problems.
MODELS:
2012 (JK) Wrangler
NOTE: This bulletin applies to vehicle equipped with a 3.6L engine (sales code ERB)
built before November 1, 2011 (MDH 1101XX).
SYMPTOM/CONDITION:
The customer may experience a Malfunction Indicator Lamp (MIL) illumination. Upon
further investigation the Technician may find that any of the following Diagnostic Trouble
Codes (DTC's) have been set.
a. P0441 - Evap Purge System Performance
b. P0420 - Catalyst Efficiency (Bank 1)
c. P0430 - Catalyst Efficiency (Bank2)
d. P0133 - O2 Sensor 1/1 Slow Response
e. P0153 - O2 Sensor 2/1 Slow Response
f. P0300 - Multiple Cylinder Misfire
g. P0301 - Cylinder 1 Misfire
h. P0302 - Cylinder 2 Misfire
i. P0303 - Cylinder 3 Misfire
j. P0304 - Cylinder 4 Misfire
k. P0305 - Cylinder 5 Misfire
l. P0306 - Cylinder 6 Misfire
m. P0835 - Clutch Pedal Switch "B" Circuit High Manual Transmission Vehicles Only
Thanks a bunch for this. Its Toyota and their standards. They decide the P0420 regardless of the state's emissions. Thats bull! Unfair! The anti-fouler counters that, when the state fails you, then buy a cat, Till then, lights out for $6