Originally Posted by tcfuller
2008 Grand Cherokee Limited 90,000 miles. We have been trying to find the source of this code for five months have no idea what to try next. To start, we hear what sounds like an exhaust leak when driving, fuel injectors are incredibly loud at idle and most recently the car stalled while at a red light. Have tried the following to fix it:
purchased all new O2 sensors
Changed spark plugs
Changed exhaust manifold gasket - passenger
Smoke tested the exhaust (twice) no leaks found
This code keeps coming back after 30-45 miles after cleared and we are averaging 15 MPG. Any advice on where to look next would be MUCH appreciated .
The exhaust leak sound you may be hearing could be an actual exhaust leak which could throw that code. I know you said you did a smoke test but the engine under load could be making that leak apparent. So with that said you should visually inspect the mid pipes and the manifolds and also the wiring from the 02 all the way back.
Secondly, double check that your headers and mid pipes are torqued down properly. On my old 5.7 the lower bolt closest to the fire wall loosened up bit.
Lastly, if your cats aren't flowing correctly sometimes and its rare but could be a possibility it will pop that code because the exhaust isn't flowing fast enough by the sensor and the computer notices this as a slow response but its not bad enough to warrant a downstream 02 code.
***I forgot to add, what brand 02 sensor are you using? Sometimes aftermarket ones can cause this...