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RUIDOSO JAMES 08-07-2013 11:50 PM

2006 jeep liberty check engine light on
I replaced my catalytic converters with a new set of direct fit cats about a month ago. At that time i also replaced all four o2 sensors with bosch sensors. The next day, the check engine light came on. Took it in to have the codes read. The only code that its showing is 0300, multiple cylinder misfires. The engine has 130,000 miles with all scheduled maintenance performed on time. I have new spark plugs in it as well. The mechanic is saying i should change my coil packs. This will cost over $150.00, and i'm not convinced that it is the problem. I think there is something from replacing the catalytic converters that has caused the light to go on, as the light has never come on since i bought it new in 2006. One other thing it just started doing, it is hesitating when you press the gas pedal. Not all the time, but occasionally.(i'm thinking this could be caused by the o2 sensors) check engine light turns off after a while, but comes back on each day. The majority of the time it is running perfect. This is so confusing. Not sure what to do from here.

Frango100 08-08-2013 01:30 AM

Re: 2006 jeep liberty check engine light on
Jeeps in general are alergic for Bosch O2 sensors:D. Most of the problems occur due to the slower heating of the Bosch sensors compared to the OEM (Denso) sensors.
If you have a scanner which shows live data, you could check the fuel trims, which probably are negative, making the fuel/air mixture too lean and causing misfires and hesitation on acceleration. Just disconnect the upstream sensors for now and testdrive. If the hesitation and misfire is gone, change the upstream sensor with Denso sensors. You will get other codes due to the disconnected O2 sensors, but it has to be reset anyway. Without the O2 sensors connected, there will be no fuel trimming and the PCM regulates in open loop, but then you know that sensors are the culprit.

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