JEEP EXPERTS ONLY!! Post catalyst fuel trim lean bank 1?? HELP!!!?JEEP Post catalyst fuel trim lean bank 1?? HELP!!!? I have a 2005 Jeep Wrangler 4.0 L . Check engine light is on, and scan tool says Post catalyst trim lean bank 1 . MPG's are down also, but runs good. Can anyone please advise me on what to start looking for??? I doubt it's an O2 sensor. | |
Your getting deep into scan-tool land and without it it will be hard to check, you have an indicated lean condition, simple things first, left side exhaust leak, possible, if not check the o2 sensor connection, its a 4 wire which means it has a heater that helps get it up to temp so the o2 can read the Oxygen vs. fuel left over for the cylinders on the left. So if the connection is good all, systems generally go to 500 mv when the key is on engine is off, and this is when you need the scan tool. If its 500 mv the wires are good suspect the heater check for power on key up to the o2 connector, if there is power and ground then you would swap the o2. If the is no power ground or reference voltage 500 mv then check farther up the connections until you get to the control module. Always check power and ground to the control module before suspecting it. If it can not supply power or ground to the heater it will not work. Remember o2 voltage goes up to 1000 mv / very rich and down to 0 mv very lean your below 500 mv most of the time, good chance of possible injector not delivering enough fuel, possible MAF, Vacuum leaks, intake leak on left side, if you use K&N oil it may skew the MAF but it will usually affect both sides... What does the readings of the right bank o2 look like or compare the front and rear o2 readings on the left bank as you force a lean then rich condition if one does not respond, start there., hope this helps..
There is a software update available for the ECU. Specific to this code. I recommend this before replacing anything.
