I'm getting a P0138 and P0172 engine code

[joecal]

Hello, I'm new here and I bought a 2003 Ram 1500 4.7, regular cab,short bed, 4wd with 65,600 miles on it. The check engine light was on when I bought it. I changed both O2 sensors, the map sensor, and the catalytic converter but it's still showing the same codes. It has a K&N cold air intake that was on it when I bought it. I was just wondering if that might be part of the problem, the engine seems to run fine. When I bought the truck it only had the P0138 code showing, not the P0172 code, now it's showing both. I really like the truck and it's in nice condition for it's age and has the typical rust issues in the early stages. Any help is appreciated.

 

[joecal]

Well I'm down to one code now, a P0172 and I'm still trying to figure that out. I believe the motor has a performance chip installed and maybe that's part of the problem. I'm going to run premium gas and see if that helps. There's a sticker on the rear window that has an e with a space(letter missing) chips but the beginning of the word is missing, so it may be Superchips but I'm just guessing.

 

[JohnnyMac]

I'd start by cleaning the MAF as that may be throwing things out of whack and causing the problem. Also, a clogged catalytic converter might do this. P0172 is too much fuel in the exhaust gases and P0183 is downstream sensor lack of O2, but I suppose too much fuel in the exhaust could cause P0183. Too much fuel in exhaust also clogs up cats. Does it smoke (black smoke) or is the exhaust pipe black and sooty? Also, does the temperature gauge work? If the temp sensor isn't working, the truck will run in "cold engine" mode and that will be rich as well.

 

[joecal]

This is an old thread that I started, but I still have a P0172 code I can't get rid of. My emission test is way overdue and I need to pass that before I can renew my license plates. I've replaced or had shops replace quite a few parts and it's gotten very expensive. I've had it to three different mechanics and they can't figure it out. The last one said it was due to low compression, the lowest reading was 125lbs. and the highest 140lbs. The engine runs fine and it's not burning oil, the spark plugs look fine that I replaced over a year ago. Any help is appreciated, this has me stumped. I don't want to keep throwing money at it.

 

[Marley]

Did the previous owner leave the tuner with the truck ?

It's possibly running a little rich with a performance tune.

 

[LoneWolf3574]

So it's safe to assume you've replaced the spark plugs and at least the driver side pre-cat O2 sensor?
Have you checked the fuel injectors and the associated wiring?
Normally I'd also suggest checking your fuel pressure at the rail, but only Bank 1 is affected by the code you gave.
Have you replaced the MAF sensor and/or inspected its wiring? This plays an important part in determining the amount of air being pulled into the engine.
Have you had the PCM flashed to the most recent version? Sometimes that will work by overwriting the performance tune IF it was flashed with one.

Sorry if it seems kinda random, I'm just throwing some thoughts and ideas out there.

 

[joecal]

Thanks for the replies. No I don't have the tuner and I'm not sure if one was used, I was just speculating. I replaced the ECU with a refurbished one and it made no difference. I was still getting the same code so I re-installed the original ECU. Yes I replaced the spark plugs and both O2 sensors several times. The last shop checked the fuel injectors and said they'r not leaking and the fuel pressure seems fine. I did replace the MAP sensor and the wiring seems okay. I haven't had the PCM(ECU) checked for updates, so that's a possibility. That would be nice if that was the problem.

 

[joecal]

This is an old post but I thought I would leave an update. I finally got the check engine light to go off. I read that ethanol runs leaner than regular gas and since code P0172 is a rich code I thought I'd try it. I used E85 and the cel went off that same day. I went in for my emission test the next day and it passed. There is a label on the hood that says you can use E85 on this truck. I had the truck up for sale and it sold a week later. I really liked the truck but the rust was getting worse on it and that's why I sold it. I also did change the fuel injectors and the fuel pump prior to this and it made no difference.