My service engine light keeps coming on and the engine runs rough until it goes out which happens when the engine warms up.
Looks like you need some real help, please allow me to provide input:
First, the oxygen sensor is def NOT your problem. Period. Why? Because the oxygen sensor does not start working until it reaches 650 degrees F. Since you speak of running rough COLD, the O2 sensor is not yet heated up, and it is ignored until it warms up, and then you state that the engine runs good. This eliminates the O2 sensor 100%, as it is controlling the Air/Fuel with a warm engine. Which means that the O2 sensor is WORKING CORRECTLY.
So, what you have is an engine condition which is running in what we call "Open Loop", where the ECU sends predetermined injection, with the two main inputs being coolant temperature and Air temperature. One or the other could be bad, which may explain the check engine light. It would be nice to know what the DTC code(s) are, the reason for the service light coming on.
I would check the fuel, Pick up some fuel conditioner at your local store dump in in then try starting it the next day. If it still runs rough the oxygen sensor(s) may be the cause of the problem, When is the last time you changed the Glow Plugs ETC?
Might be there is some chocking in the diesel tank; so first check tham.
Thanks for using FixYa
Hi! It can mean diffrent for diffrent cases. It can vary from a loose engine cap to misfiring. Low oil pressure or faulty radiator can also trigger this problem, check for that. However, you are saying it is making a rough noise then it means there is a problem of serious engine trouble and you can't ignore it. Call a mechanic as soon as possible because there is user repairable part in engine. Contact Onstar if you have the subscription.
The O2 sensor is mounted on the exhaust mainfold, however you do not know if it is the oxygen sensor or any other fault until you have your car computer module scanned using an ODB II code reader.
See:
OBD-II - On-Board Diagnostic System
To buy a code reader:
A30 OBD II DTC Data Code Reader
INNOVA® OBD-II CAN CODE READER
OBD2 Code Reader - OBD II
Have you recently changed where you buy your fuel. i would try a few bottles of fuel conditioner and let it sit over night and see what it runs like the next day.
Robert
You are having Oxygen sensor problems, have the truck scanned while the light is on to confirm this or just save the diagnostic fee and replace them yourself. Good luck!!
There will not be just one answer that you can fix and be done the first time with the general problem you posted that your vehicle is having. We gave you some idea's based on the little info we have on your vehicles problem. You will have to afford to have it scanned for fault codes to pinpoint exactly what it is if you have tried everything suggested and your still having the problem.
Oh and your oxygen senors may still be the problem but you won't know until you have it scanned like I said. Being "stuck in open loop" refers to the oxygen sensors not functioning properly most of the time so save the trouble and call autozone and see if they can scan your computer for free or pay to find the problem.
unfortunatly it is the computer this has happened to my truck twice
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This is a diesel. Where is the oxygen sensor
I added some fuel conditioner with no help. Now what?
If i would have afforded a computer for my truck I would not have to do this. Would you please repost my problem.
I said it runs rough not sounds noisy
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