1998 jeep grand cherokee larado 4.0

i have a check engine light on and i cant get rid of it . I took it to auto zone and they did a scan on it and it was 3 codes.
1 P0420 2. PO351 3. PO108
ok oxygen sensor, map sensor, and coil i replaced all 3 and then went back and he reset the codes and i was ok for 1 day and they r back.
then i went back up to auto zone and he scaned it and bam they r back then he said just drive it for 2 days maybe computer will reset this was december 2014 i am lost here . so i called a dealership they said u might need a new computer at 750 bucks . Help and oh by the way the jeep has a bad stalling problem with a bad moldy foul smell when he stalls i let it sit a while and it runs badly//

1 thought on “1998 jeep grand cherokee larado 4.0”

  1. Looking at these codes together and with your input about the foul smell, I would think that your sensors are working as they should and that the foul smell is being caused from a RICH condition. This can happen form a vacuum leak. The sensors would try to dump more fuel in and the excess would flow tot he converter and make it hotter than normal and sometimes melt the inside and making it inefficient and also create that awful smell. Although it is possible that the ECM is faulty, I would replace it as a last resort.

    P0420 – Catalyst System Efficiency Below Threshold Bank 1

    The Common Fix is to replace the catalytic converter after you have made sure your O2 Sensors are working as they should.

    Possible causes
    – Three way catalyst converter Bank 1
    – Exhaust tube
    – Intake air leaks
    – Fuel injectors may be faulty
    – Fuel injector leaks
    – Spark plugs may be faulty
    – Improper ignition timing
    – Engine Control Module (ECM)

    P0351 Jeep – Ignition Coil 1 Circuit

    Possible causes
    – Faulty Ignition Coil 1
    – Ignition Coil 1 harness is open or shorted
    – Ignition Coil 1 circuit poor electrical connection
    – Faulty Engine Control Module (ECM)

    P0108 Jeep – Manifold Absolute Pressure Sensor Circuit High

    Possible causes
    – Faulty Manifold Absolute Pressure sensor
    – Manifold Absolute Pressure harness is open or shorted
    – Manifold Absolute Pressure sensor circuit poor electrical connection
    – Faulty Engine Control Module (ECM)

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