MIL Codes

Speedo

Speedo

Member
Joined
Apr 16, 2017
Messages
37
Location
Madisonville, LA, United States
'04 4.0L w/ 145k miles.

Runs fine, I think. The dingleberry at Autozone told the girlfriend I need to replace the cat(s).

What are y'all's thoughts on this? Codes below:

P0442-EVAP LEAK MONITOR MEDIUM (0.040) LEAK DETECTED

P0455-EVAP LEAK MONITOR LARGE LEAK DETECTED

P0432-2/1 CATALYTIC CONVERTER EFFICIENCY
 
The evap leaks could caused by a leaky gas cap, having started the engine with the gas cap off, or a leak in the evaporative system. Ask your girlfriend if she has recently started the engine with the gas cap off.

A code indicating a bad catalytic converter can of course be caused by a bad cat, but that kind of code can also be caused by a bad downstream O2 sensor which is what checks the efficiency cat.
 
She only lets me drive MY Jeep when it needs gas. Buuuut, I have filled it up with the engine running, could cause that? Wouldn't the light go off after a few start ups?

True, I would hate to replace a cat because of a faulty O2 sensor, and then still have a problem. Should I just replace the O2 sensors and hope that's it? Thanks Jerry
 
Speedo said:
I have filled it up with the engine running, could cause that? Wouldn't the light go off after a few start ups?
Click to expand...
Yes unscrewing the gas cap with the engine running will cause that code. Try resetting the computer by disconnecting the battery's negative lead for 2-5 minutes then reconnecting it. You'll lose your radio presets and clock setting but that will clear the code right away.

Always shut your engine off when adding gas to the tank and reinstall the gas cap before starting the engine.
 
I will try that when i get back home.

I have a bad habit of never shutting off my truck to gas up... Guess I need to break that :eusa_doh:

Regarding the O2/cat issue, I'm just going to replace the sensors and see what happens.
 
Speedo said:
I will try that when i get back home.

I have a bad habit of never shutting off my truck to gas up... Guess I need to break that :eusa_doh:

Regarding the O2/cat issue, I'm just going to replace the sensors and see what happens.
Click to expand...
Make sure to ONLY use NGK or NTK O2 sensors. Especially make sure to never install Bosch O2 sensors which are well known to not work well in our Jeeps.
 
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