Hey guys, first time posting here. I have a 2006 TJ Wrangler at around 110,000km and I've been getting terrible fuel economy and a bad idle. I replaced my spark plugs and cleaned my throttle body. It didn't fix my issue and soon after I had 2 codes - P0133 and P0153. I replaced my upstream sensors with new NGK sensors. The codes disappeared but I soon had the P0133 reappear and disappear over the next 2 weeks. I'm still getting terrible fuel economy (about 250km before the fuel light comes on) and the idle is still rough. Before I purchase a new catalytic converter and exhaust system, Is there anything you'd recommend I look for that could be causing me this issue?
P0133 code
- Thread starter djjcom
- Start date
What mpl were your getting before and what mpl are you getting now? In the US we don’t use the metric system too much so not sure what your numbers translate to and don’t feel like doing the math.
Have you ever replaced the PCM? Not saying it’s your problem at the moment but the 2006 models have known PCM failures.
You can get a back pressure gauge and measure yours to see if your catalytic converter is clogged
That's some great points to consider. I use to have that common issue with the PCM and shifting rough into first gear but the issue went away a while ago. Maybe I need to consider getting a new PCM before I replace the cat and exhaust.
@Wranglerfix
I'm sure he has some input.
I think I would test the back pressure before doing anything and make sure there are no issues with the catalytic converters.
Since you're seeing the P0133 code return intermittently, it might be worth checking a few things before you jump to replacing the catalytic converter.
Oxygen Sensor Wiring and Connections (this is a big one!): Inspect the wiring and connectors for both upstream sensor wires. Look for any fraying, corrosion, or loose connections that might be causing intermittent signals.
Exhaust Leaks: Check for any leaks in your exhaust system before the downstream O2 sensor. Even a small hole can lead to inaccurate readings which could trigger the P0133 code.
Vacuum Leaks: A vacuum leak can cause a rough idle and poor fuel economy. Inspect hoses and connections for cracks or disconnections. Pay special attention to the intake manifold.
Fuel Pressure: Low fuel pressure or a failing fuel pump could be contributing to your fuel economy issues. It might be worth testing to ensure your fuel system is functioning properly.
Catalytic Converter Condition: Lastly, if you've ruled out everything else, you might want to inspect or test the catalytic converter for clogging or failure.
Taking these steps might help you pinpoint the issue without diving straight into replacing the cat. Good luck, and keep us posted on your progress!
I took it to a mechanic to test if there was any leak or a bad cat. They said the cat isn't clogged and there were no leaks in the exhaust but apparently a small amount of smoke from the throttle body but not enough to be a problem. They said was bare cables from the 02 sensor that was arcing but they tapped it up and it didn't change anything. Anything else I could test for before I spend some big money on a new wranglerfix PCM?
How much do you trust the mechanic? Although the mechanic taped up the bare cables, it's essential to ensure that the wiring is completely intact and secure. Consider replacing the harness if it looks worn or damaged. There's a good chance that you've got more areas like this throughout your wiring harness.
I'd consider sending your PCM to @Wranglerfix to have him test it. Mark is an honest guy and if your PCM is fine he isn't going to try and sell you a new one.
The occasional hard shift from 1st to 2nd in the morning is the Pcm failing. It will not cause the check engine light to turn on. The P0133 is a fault that is also pcm related.
The mechanic seemed honest and didn't even charge me for looking at it as he couldn't diagnose the problem. I will have a look at the wiring myself though.
I hear good things about wranglerfix but I'm in Australia so no chance of getting mine tested and If i go forward with a new one its going to cost $295 usd for delivery. Really hoping to exclude all other possibilities but i'm getting about 140 miles before my fuel light comes on so its becoming too expensive to drive
Yeah shipping would probably be costly but Mark is definitely the go to guy for replacement PCMs and testing.
I'd take a serious look at the wiring harness which may require really digging into things. Often times if one section of the harness is like that, you'll find more if you dig. Your problems to me seem indicative of this.
Do you know if there's a way to find what voltage the 02 sensors should be at? I'd assume if its a faulty 02 sensor with bad wiring I could monitor it using the OBD scanner and see something that isn't normal there right?
While I haven't checked personally, I'm 99% certain it will tell you in the factory service manual what voltage they should be at.
I wouldn't pay to ship your OEM PCM to Mark. If it's an OEM, it's going to fail eventually and can't be fixed. You'd be better off putting that money towards his rehosted one.
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