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C6 Corvette ZR1 & Z06General info about GM’s Corvette Supercar, LS9 Corvette Technical Info, Performance Upgrades, Suspension Setup for Street or Track
The car ran perfect until one time at cold start the car idled perfect and suddenly it rough idled and a check engine light came on.
the codes are:
p0191
u1802
p069E
p2635
p0171
p0174
p0506
I cleared the codes and start the car again these codes came back
p2635
u1082
I took the car to the shop know it been there for 3 weeks and they couldn’t figure the problem.
first assumption was the fuel pump controller module relay.
as The fuel pump controller module relay is 1400$ I didn’t want to spend that amount and I’m not sure if it will solve the problem.
after further investigation we found that if we start the car every day the car run perfect without any problem.
If we stopped the car for 2-3 days the problem return back.
First off find yourself a diagnostic shop that knows how to diagnose cars instead of a generator repair shop or dealership that will only guess…FYI on your P2635…shouldn’t take 3 weeks to diagnose this.
Mine did the same thing but only threw P0191 and P069E codes. Local shop could find nothing wrong. Driving the car more seems to take care of the problem. Have owned the car for 10 years and this never happened before.
It's something but as of now, a mystery.
The car ran perfect until one time at cold start the car idled perfect and suddenly it rough idled and a check engine light came on.
the codes are:
p0191
u1802
p069E
p2635
p0171
p0174
p0506
I cleared the codes and start the car again these codes came back
p2635
u1082
I took the car to the shop know it been there for 3 weeks and they couldn’t figure the problem.
first assumption was the fuel pump controller module relay.
as The fuel pump controller module relay is 1400$ I didn’t want to spend that amount and I’m not sure if it will solve the problem.
after further investigation we found that if we start the car every day the car run perfect without any problem.
If we stopped the car for 2-3 days the problem return back.
any one faced the same problem?
Need to understand the situation a little better.
You said you start the car everyday and no problem but you let it sit for 2-3 days then start it and the problem returns. When you start the car, are you just letting it idle in the garage or are you driving it until coolant and oil temps are normal?
Without knowing the ans. to the above, the combination of faults you list in the OP tells me the ECM "thinks" the engine is running out of fuel because you have a fault with the fuel pump controller, both front O2Ses are lean and the idle speed is below spec.
The P2635 sets when the difference between commanded fuel pressure and delivered fuel pressure is out of range. It's a shame you cleared codes because the failure records might have provided a clue to the cause of that.
A wide variety of repairs (New fuel pump module, new fuel pump, new injectors, fuel pipes) are possible for solving this fault. To solve it requires a dealer-level scan tester. Solving the DTC may also require road testing which might need to be pretty aggressive.
Last edited by Hib Halverson; 08-31-2023 at 12:09 PM.
First off find yourself a diagnostic shop that knows how to diagnose cars instead of a generator repair shop or dealership that will only guess…FYI on your P2635…shouldn’t take 3 weeks to diagnose this.
they tested the circuit as they found that there is problem with the current as the fuel pump controller module relay or the fuel pump controller module does not supply sufficient current ( some times ). Some times the car run without any problem
Mine did the same thing but only threw P0191 and P069E codes. Local shop could find nothing wrong. Driving the car more seems to take care of the problem. Have owned the car for 10 years and this never happened before.
It's something but as of now, a mystery.
The problem happened to me suddenly and it remained for 5 days. After I took the car to the shop they found that the car run fine some times. They couldn’t know how to generate the problem or how to avoid it or how to solve it. They think it is either from the fuel pump controller module relay or the fuel pump controller module.
You said you start the car everyday and no problem but you let it sit for 2-3 days then start it and the problem returns. When you start the car, are you just letting it idle in the garage or are you driving it until coolant and oil temps are normal?
Without knowing the ans. to the above, the combination of faults you list in the OP tells me the ECM "thinks" the engine is running out of fuel because you have a fault with the fuel pump controller, both front O2Ses are lean and the idle speed is below spec.
The P2635 sets when the difference between commanded fuel pressure and delivered fuel pressure is out of range. It's a shame you cleared codes because the failure records might have provided a clue to the cause of that.
A wide variety of repairs (New fuel pump module, new fuel pump, new injectors, fuel pipes) are possible for solving this fault. To solve it requires a dealer-level scan tester. Solving the DTC may also require road testing which might need to be pretty aggressive.
I used to drive the car every weekend. The problem happens at cold start some times. As soon as the rpm comes down then the car start to run rough and all codes starts to come. When we started the car and tested there was no issue with car (road tested). However some times at cold start the problem happens we don’t know how to generate it. Even sometimes if we keep the car for 4 days and start the car the car run fine.
Mine did the same thing but only threw P0191 and P069E codes. Local shop could find nothing wrong. Driving the car more seems to take care of the problem. Have owned the car for 10 years and this never happened before.
It's something but as of now, a mystery.
I have the same problem. Previously had codes: p0191, p069e, p2635 and u1802. Now I only have a consistent u1802. Performed a pin slip test as well as check connections for corrosion. Looking into diagnostics this weekend to differentiate between a CAN bus issue or module. I believe the 20877840 Fuel pump driver module needs to be programmed. Does the 25910000 Fuel pump driver control module relay need to be programmed?
The relay is plug and play the fuel pump control module will need to be programmed to the car. Try disconnecting the battery and fully charging it then reconnect the battery as it worked for me now no codes show up. Get a battery tender or fully charge the battery before you drive it as yesterday I went to drive the car after letting it sit for a week and the same issue popped up and threw the codes. I charged the battery over night to 97% and today it started and I drove it for a couple of hours with no issue.
Thank you for the reply. Mine has been on the battery tender for some time now and hasn't changed the outcome. Hopeful tomorrow will shed some light on things.
08-29-2023, 12:18 PM
Zr1 rough idle
