SayreJK07

New motor. Ran pretty good for a couple weeks. Check engine light came on and the Jeep was running rough. Pulled the codes and got...
P0137
P0300
P0420
P3750
P2173
C121C
B210D

Need help pretty bad. This piece of shit is about to get sold if I don't get it running and have fun with it anymore.


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SpicedCrusher

Codes I could find

SayreJK07

Thanks. Anyone with some possibilities for troubleshooting this. Bad Cat or O2 sensor?

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SpicedCrusher

A code P0137 may mean that one or more of the following has happened: Faulty o2 sensor. Exhaust leak near the rear sensor. Plugged catalyst Short to voltage on O2 signal circuit. High resistance or open on O2 signal circuit. Engine running very rich or lean. Engine misfire condition. Fuel pressure very high or low - fuel pump or pressure regulator

A code P0300 may mean that one or more of the following has happened: Faulty spark plugs or wires. Faulty coil (pack) Faulty oxygen sensor(s) Faulty fuel injector(s) Burned exhaust valve. Faulty catalytic converter(s) Stuck/blocked/leaking EGR valve / passages Faulty camshaft position sensor Defective computer.

A code P0420 may mean that one or more of the following has happened: Leaded fuel was used where unleaded was called for. A damaged or failed oxygen sensor (HO2S) Downstream oxygen sensor (HO2S) wiring damaged or connected improperly. The engine coolant temperature sensor is not working properly. Damaged or leaking exhaust manifold / catalytic converter / muffler / exhaust pipe. Retarded spark timing. The oxygen sensors in front and behind the converter are reporting too similar of readings. Leaking fuel injector or high fuel pressure. Cylinder misfire Oil contamination

A code P2173 Check the EGR connection/gasket at the top of the intake plenum. Also, check MAP sensor and make sure O ring is good and that it is locked into position.

A code C121C usually means a problem in the PCM (on-board computer) or the Anti-Lock Brake Module. There is a quick test to determine which is at fault, unfortunately, it requires the use of a scan-tool.

Huntphreak

Start with the basics:

That is alot of codes, check you battery Voltage first, if it is not 12V or above both running and not running change that first!!

Electrical things usually work pretty poorly with out electricity

Huntphreak

Do you have access to a volt meter?

The more I read through the codes I think you need a new battery. Either it is old and not holding a charge due to crud on the plates or you blew a cell inside, (ie it will read like 5.5V or something really low).

Everything else could just be a trickle down effect. Once you confirm the battery status, check the alternator output voltage, this should be around 14V or so when running.

SpicedCrusher

x2

The more I think of all the different codes it's definitely got to be an electrical issue. Good place to start. Too many random codes.

SayreJK07

I'll get to autozone and get it tested.

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Huntphreak

That'll work, they can put a load on the battery and give you a result. Takes a few minutes.

If for some reason the battery checks out GOOD, or you get a new battery and continue to have issues go next to the alternator.

Sometimes a good battery and a bad alternator will put out just enough voltage for short periods of time to piss you off. Let you drive down the road and then die

Every time a cylinder fires it takes a little juice, with a bad alternator and a good battery the battery can run the jeep for a short while till it drops below the low voltage threshold (7V i think) then apocalyptic shit starts happening, and the laws of physics start to collapse...

SayreJK07

Battery good. Alternator showed bad, but barely. I have an infrared temperature gun to check the cats after work. I was getting some rattling in the passenger cat area after releasing the throttle. So one of them might be bad.

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