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CEL P0138, P0141, P0456 and P0500

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4.2K views 18 replies 7 participants last post by  Kaptainkid1  
#1 · (Edited)
So I've been driving around for the last 4000 miles or the last year with a check engine light. Living in California you can not register your Jeep if it has CEL. Smog is coming around now I have fix these problems.

I fix P0500 because my odometer cable plug had popped off and I replaced it and that CEL P0500 is gone.


P0456 is small Evap leak and I know this doesn't effect the Jeep performance. I'm process in tracking down this problem. My gas cap is new, checking my gas rubber lines and checking my Purge solenoid.

I know P0138 and P0141 is an O2 sensor down stream and I wanted to know if these failed sensors and running the Jeep for the last year could have hurt or damaged the Jeep? I ignored these CEL because the Jeep ran fine and had no noticeable driving issues.
Also when I replace the O2 sensor with NGK NTK sensor will I noticed any difference?

No smoke, not burning oil and no major engine problems ever. All ways ran good and has never failed ever. Engine has never been taken apart except for clutch and RMS.

2002 Wrangler 4.0l manual with 170k.
 
#4 · (Edited)
If you had upstream O2 sensor codes, running bad upstream O2 sensors could do damage by dumping too much fuel or running too lean. They regulate the air/fuel mixture. These are the sensors that can really make a difference in how well the engine runs. You would not see significant improvement in MPG, but if the sensors were bad, new ones would smooth things out and just run much better.

You say you have no codes for upstreams, so that is good news.

Downstream is less likely to do anything impacting your engine, since it is just reporting back to the computer on whether the catalytic converter is performing its job or not. It is there mainly to satisfy the EPA requirements to ensure emissions are within design specifications for the vehicle.

Your mini-cats look good. At least you had honeycombs! One of mine was completely blown-out and blocking the main catalytic converter a lot and the one that remained was more than 50% clogged.
 
#5 ·
So........Living in California

I know P0138 and P0141 is an O2 sensor down stream and I wanted to know if these failed sensors and running the Jeep for the last year could have hurt or damaged the Jeep? I ignored these CEL because the Jeep ran fine and had no noticeable driving issues.
Check for exhaust leaks at or forward of the cat ending flange.
 
#6 ·
P0138 (M) - O2 Sensor Circuit High Voltage (Bank 1 Sensor 2) - Oxygen sensor input voltage maintained above normal operating range.

P0141 (M) - O2 Sensor Heater Circuit (Bank 1 Sensor 2) - Oxygen sensor heater element malfunction. O2 sensor voltage greater than 3 volts for 60 to 240 seconds.

Since you have codes for both the sensor input/output & heater circuits I would carefully inspect the wiring first. Especially look where the wiring might be or have been in contact with the exhaust.

If wiring good maybe a bad sensor.
 
#7 ·
I pulled the sensor off and checked all the wires to my O2 sensor. I went back and checked the O2 exhaust pipe to make sure all the seals we're sealing properly. No exhaust leaks. I suspect my O2 sensor is failing or is failed. So none O2 sensor wires are in contact with any exhaust or body parts. The wire are fully intact. No exposed wires.
I decided to carb clean the O2 sensor since if they are dead this wouldn't kill it. I also wire brush the sensor to pull off any carbon deposits. Cleaned the sensor until it was back to bare metal. Shoved the sensor back in and drove 100 miles. Cross my fingers but the P0138 and P0141 is gone for now.

I have P0456 small evap leak to deal with. I pulled the Evap purge solenoid located by the intake manifold. Shot some brake cleaner and tested with a 12 volt battery to the leads. The Purge Solenoid opened and closed no problem. I put a rubber hose and was blowing air and can hear the valve opening and closing with 12 volt connection. So that part is functioning.
I even went to the fuse box behind the glove box and change any fuse that were possible failures. New fuse for PDC and HBL SW. Eventhough all the fuses look good.
I had dropped the gas tank last month to put in a new gas filter and I checked all the rubber lines and they were all good. Plus I have a new gas cap as 4 months old. So I know this area of a possible evap has been dealt with.
Let see if this cleaning and addressing the Evap components will address my P0456 leak.. crossing my fingers!

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#9 ·
IIRC in CA it requires at least 40 clean starts to qualify for smog. I just went through the same thing. I had a P0456 as well. I reset the PCM/ECM (disconnected battery) and fortunately the P0456 didn't pop up again until after it was smog tested. I have to trouble shoot my system now. [emoji24]

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#14 ·
On my TJ my state allows one readiness monitor not ready and I had disconnected battery while not using
Needed emissions drove till all by evaporate were ready and passed that way

Check your state/county epa rules as depending on year even feds may be ok with one monitor not ready


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#15 ·
Apparently California allows 1 readiness monitor for EV only since 2017. Honestly I'm not sure how valid that information from a website might be.
My Jeep just pulled another code and its P0442 now.
Oh jesus are these CEL code going to end? It's another EVAP error. I'm going to do a smoke test next.

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#16 · (Edited)
I pulled the gas tank down a second time and this is what I found. A month ago I changed the gas tank strainer and I guess it didn't seat well. The plastic ring and rubber o ring needs to be installed properly. The second time I made sure to seat the rubber ring properly because is pops off very easily. Secondly the plastic locking ring is very difficult to lock down. I used vaseline on the threads and it made it easier to set the locking ring. Also since this was my second time I found out cleaning the area and taking off any dirt help mat the surfaces. So my leak happened to be a problem I caused months ago.
This time I put my mouth around the gas tank filler neck and blew air in the tank to see if the seal was air tight before installing the gas tank back. So after 10 miles P0456 came back and P0442 went away.
1 step forward and 2 steps back is my motto.

So back to the original P0456 evap leak. I put soapy water all over the gas cap and charcoal canister under the hood. Ran the Jeep for an 1/2 hour and applied soapy water all over the hose and connections. Showed no leaks.

Next going to buy a new gas cap and purge solenoid since its only $50 for both parts.

Blowing air in gas tank and you can see the leaking bubbles on top seal.
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The rubber seal sits between the float and the plastic gas tank. This seal easily gets crushed and crimped. Its fallen into the tank a couple times. Vaseline helps keep the rubber and plastic from hanging up.
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#18 · (Edited)
I checked the Natural Vacuum Leak Detection Pump on the Jeep Wrangler and it seems it's working according to the youtube video on how to check it. I bench test this part and my concerns would be the electric wires on the Jeep isn't sending the proper signal to this Vacuum pump. I hooked up a volt meter and after 30 second its sending 13.4 volts. I'm guessing its the proper voltage.
I bought a junkyard VLDP pump and it didn't fix the problem either I'm guessing it's broken too or my jeep wiring might be the issue. Since my Jeep is still pulling a P0456. I also replaced the gas cap with a new OEM Mopar part and the P0456 didn't fix it either.
I've vacuum checked the system and it holding pressure basically it's like the smoke test but haven't found any leaks.
What next?
I checked the gas tank, all the rubber hoses, gas cap, VLDP pump and the purge valve. It's all tested and working and still have P0456.

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#19 ·
Here is where I think I have a problem but can't figure how to test it.
I think it's the VLDP pump is broken or maybe the electric line to the pump maybe the issue. I found a youtube video on how to test a LDP pump and my pump and back up pump is working according to this YouTube DIY.



Once the LDP pump is plug in to the TJ, I'm not getting any pressure in the LDP pump line out but when I bench test it and trigger the pump manually it blows up the balloon.
So here is the issue I tested the female line from the engine bay and with a voltmeter I'm getting 13.5 volt from the leads. We have 3 leads in the plug and two leads trigger 13.5 volt but no pulsating. I'm guessing it should pulse base on the youtube on how to bench test.
Doesn't anyone know for sure if these electric leads should just send constant volts to the VLDP Pump when the engine is running?

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