Over the past year, the check engine light on my 2003 Buick LeSabre Custom has indicated a service engine soon PO404 code on three different occasions.
I have had my mechanic replace the EGR valve twice. Now, the check engine light is on again with the same code problem.
The acceleration is sluggish initially, but improves somewhat after the engine warms
Could this be something other than the EGR value?
2003 LeSabre Check Engine Code PO404
2003 LeSabre Check Engine Code PO404
If replacing the valve several times has not fixed it, then you have either a wiring problem, or a computer problem. You will need a schematic, volt / ohm meter and a scanner to diagnose this problem.
2000 LeSabre Computer or sensor problem?
I have been experiencing the following random failures:
o While driving, RPM guage drops to zero; engine continues to operate fine.
o While driving, RPM guage drops to zero simultaneous with a brief stutter or a hard shift; engine continues to operate fine.
o While driving, RPM guage drops to zero, volt indicator lights, engine dies. Sometimes I can shift into neutral, restart, and resume. Other times the engine may require several attempts to restart. Plenty of cranking power, but the engine sounds like it is not getting spark or fuel, until it restarts.
o While leaving a stop light, the engine falters and dies. It may or may not immediately restart.
These symptoms have happened relatively rarely, though the frequency has been increasing. I have never been stranded, as the restart occurs within 2-5 minutes. Sometimes (but not often) these symptoms cause the Service Engine Soon light to appear. The light disappears within 2 or 3 more times driving.
What do I need to do to diagnose the cause?
2000 LeSabre, approx 140,000 miles.
o While driving, RPM guage drops to zero; engine continues to operate fine.
o While driving, RPM guage drops to zero simultaneous with a brief stutter or a hard shift; engine continues to operate fine.
o While driving, RPM guage drops to zero, volt indicator lights, engine dies. Sometimes I can shift into neutral, restart, and resume. Other times the engine may require several attempts to restart. Plenty of cranking power, but the engine sounds like it is not getting spark or fuel, until it restarts.
o While leaving a stop light, the engine falters and dies. It may or may not immediately restart.
These symptoms have happened relatively rarely, though the frequency has been increasing. I have never been stranded, as the restart occurs within 2-5 minutes. Sometimes (but not often) these symptoms cause the Service Engine Soon light to appear. The light disappears within 2 or 3 more times driving.
What do I need to do to diagnose the cause?
2000 LeSabre, approx 140,000 miles.
Re: 2000 LeSabre Computer or sensor problem?
This sounds like an ignition module that is going bad, which is pretty common on those engines. This would explain the RPM dropout, stalling, hesitation, etc.
Since you say the check engine light has come on before, I would highly recommend getting it scanned so you can see what codes are present. Even if the light is off now, there will be something stored from the previous time the light was on. This should help greatly in finding your problem, and most likely would end up being related to the ignition system or other ignition/fuel controlling sensor.
I've also seen crank sensors cause quite a bit of similar problems like you are experiencing, but usually they are heat affected and once they act up, say after driving a while, it will usually take a significant cool down period before the car will restart. You don't seem to be having that issue, but you never know.
Since you say the check engine light has come on before, I would highly recommend getting it scanned so you can see what codes are present. Even if the light is off now, there will be something stored from the previous time the light was on. This should help greatly in finding your problem, and most likely would end up being related to the ignition system or other ignition/fuel controlling sensor.
I've also seen crank sensors cause quite a bit of similar problems like you are experiencing, but usually they are heat affected and once they act up, say after driving a while, it will usually take a significant cool down period before the car will restart. You don't seem to be having that issue, but you never know.
GM Dealer Technician For 18+ Years
In the automotive industry for 20+
In the automotive industry for 20+
-
- Similar Topics
- Replies
- Views
- Last post
-
- 1 Replies
- 15987 Views
-
Last post by carriedi
Fri Nov 30, 2018 10:45 am
-
-
New post Check engine light shows running lean on bank one,what is te problem?
by Guest » Sun Sep 06, 2020 7:41 pm » in Buick - 1 Replies
- 12428 Views
-
Last post by carriedi
Mon Sep 07, 2020 4:41 pm
-
-
- 3 Replies
- 10376 Views
-
Last post by carriedi
Tue Jul 04, 2023 1:03 am
-
- 1 Replies
- 8024 Views
-
Last post by carriedi
Fri Sep 26, 2014 9:45 pm
-
- 1 Replies
- 7707 Views
-
Last post by carriedi
Tue Dec 30, 2014 10:31 pm