LB7: check engine light

country junkie

New member
Feb 15, 2020
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Im new to diesels. I just bought my first a few days ago. It is a 2003 crew cab long bed 4x4. Yesterday i changed engine oil and filter, and also changed the oil and filter on the trans, everything looked good and went good. When i started it eveything sounded and looked good except the check engine light came on. i let it idle and warm up and checked the tranny fluid level it was good. shut it off and checked the engine oil level it was fine. so i started it back up and the check engine light was still on. Any ideas/
 

DAVe3283

Heavy & Slow
Sep 3, 2009
3,327
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Boise, ID, USA
ReaperLegion.net
You're going to need to get the codes read. These trucks are advanced enough there's no point guessing what might have it unhappy. Most auto parts stores will read codes for free.

Post back what code(s) are set, and we can help you out.
 

country junkie

New member
Feb 15, 2020
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The codes they pulled today were p0087 and u1000. Cleared them both out and check engine light came back on. I haven't been back to see what popped again.
 

ZeroGravity58

Active member
Mar 23, 2008
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Maryland
P0087 is a low fuel pressure code. If you don't have a lift pump try changing out the fuel filter. It could be plugging up. The U1000 is a class 2 communication code. Maybe a dirty/bad ground somewhere
 

DAVe3283

Heavy & Slow
Sep 3, 2009
3,327
13
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Boise, ID, USA
ReaperLegion.net
Did the code come back on immediately, or once you started driving?
You're going to want to find someone with a scan tool and watch the Commanded FRP and Actual FRP values. It could be a plugged filter, or a weak CP3, or failing injectors, or a bad FRP sensor.
 

country junkie

New member
Feb 15, 2020
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I've had it cleared 3 times. It came on immediately all three times.

Earlier this evening I started and let it warm up and the check engine light was off. I drove about 30 mins then came home to get my wallet to go to town and get an air filter for it.. when I got back in the truck the check engine light was back on. I went ahead and went to town to get a air filter. I had them clear the codes again and i changed the filter before i left. This is where it gets weird, on the way to town the truck was in limp mode. After having the code cleared and the air filter changed, even though the light check engine light came back on, the truck was no longer in limp mode. Ever since no matter if I shut it off or not the light is still on but not in limp mode.
 

country junkie

New member
Feb 15, 2020
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I do not have any way to have anyone check things on a computer, as of yet, without going to a shop. I have ordered a ppe race fuel valve. From what I've read there is a good chance the fuel pressure relief valve could be going bad. Just a stab in the dark. I'll try to get it hooked up to a computer.
 

KyleC4

Tech
Dec 30, 2016
334
6
18
Bay Area
Can’t one of those autozone type stores scan your codes for free? I’m cringing every time I read your post about just wanting to guess at what needs to be done. The cost of a race fuel valve probably could’ve gone to a legit shop to get the codes read for you.
 

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