I've been having an exhaust leak on my midpipe's resonator so I replaced it with an aftermarket one. Took it to the exhaust shop and they welded it on. They tested to see if it had any air leaks so they turn on the car and I guess there was so while the vehicle is on, they welded. Long read, but last paragraph gets to the point.

I had no problems for a few hours, but later that day car threw a P0603 code. Car still runs, but accelerator doesn't work. It's not like I use power steering. I told my mechanic what happened since he said it has to do with the internal memory of the computer. I told him what happened and he said that welding while the vehicle is on is what caused the problem.

I have a wireless OBDII reader and I'm able to clear the code, but there's no telling when the code will throw and my car will go into this limp mode again. Highly unsafe I'd add as well. He said I need a new ECU. Been through that process before and it sucked. Hard to find for an '06 sedan.

Anyhow, what I'd like to know is if welding the exhaust while the vehicle is running would short out a circuit or sensor that causes the computer to trip and lose internal memory.

 

I've never heard of welding an exhaust pipe causing electrical issues unless it was near an O2 sensor or other electronic piece. But, I'm far from an expert on electronics so I'm subbed for the answer. Sorry I couldn't help out more.

 

No worries. My buddy mentioned something similar. He said that if while welding it has a spike it sends that through the exhaust and can trip an O2 sensor possibly or whatever sensor is close by and if it's not in a proper temperature range, since connected to the ECU, it'll throw the code. Something like that.

I just thought welding while the vehicle is on is not something you're supposed to do. Also they were having issues with their welding machine. It wouldn't spark up and it took a while and sometimes it would stop working then work again. It did this while the vehicle was both on and while it was off.

 

Take Viagra for this problem Levon lol.

 

No, welding an exhaust would not cause any problems unless he was doing the repair near an O2 sensor circuit.

 

Could the increased heat on the pipe travel to the sensor and cause damage?

I had a P0447 code showing for a month or so but no problems. Then all of a sudden this after the resonator swap. Now I'm getting more codes along with these messages on myobd ii scanner.

 

You running any kind of tune?

 

For P0447 Check your evaporator canister for control valve operation

For P2122 try cleaning your TPS sensor and connector. Make sure there is no moisture or corrosion (probable cause faulty sensor)

For P2138 do the same for the accelerator pedal position sensor (probable cause faulty sensor)

and P0643 - Faulty Engine Control Module (ECM)
- ECM harness is open or shorted
- ECM circuit poor electrical connection
- Shorted sensor on 5 volt circuit

All issues could be related to a bad ECM

 

Try this first though

ECU Resetting Procedures
Timing is extremely critical. If it is NOT DONE within the specify time, the ECU will
not reset and the Check Engine Light (CEL) will continue to remain ON.
A stop watch or an analog clock with a second’s needle will be useful.
Operations Procedures
1. Confirm that accelerator pedal is fully released, turn ignition switch “ON” and wait 3
seconds.
2. Repeat the following steps (2a and 2b) procedures quickly five times within 5 seconds.
2a. Fully depress the accelerator pedal (HARD).
2b. Fully release the accelerator pedal.
3. Wait 7 seconds, fully depress the accelerator pedal and keep it for approx. 10 seconds
until the CEL starts blinking.
4. Fully release the accelerator pedal (while the CEL is still blinking)
5. Wait about 10 second.
6. Fully depress the accelerator pedal and keep it for more than 10 seconds.
7. Fully release the accelerator pedal (The CEL light will continue to blink).
8. Turn ignition switch to “OFF” position and now you can start the car. The CEL light
should be gone.
If the CEL light continues to remain ON, repeat the above steps. Timing is
EXTREMELY critical to resetting the ECU.
Accelerator Pedal Release Position Learning
Operation Procedure
1. Make sure that the accelerator pedal is fully released.
2. Turn ignition switch “ON” and wait at least 2 seconds.
3. Turn ignition switch “OFF” wait at least 10 seconds.
4. Turn ignition switch “ON” and wait at least 2 seconds.
5. Turn ignition switch “OFF” wait at least 10 seconds.
Throttle Valve Closed Position Learning

Operation Procedures
1. Make sure that accelerator pedal is fully released.
2. Turn ignition switch is “ON”.
3. Turn ignition switch is “OFF” wait at least 10 seconds.
Make sure that the throttle valve moves during above 10 seconds by confirming the
operating sound.
Idle Air Volume Learning (Throttle Position Learning)
It is better to count the time accurately with a clock.
Operation Procedures
1. Perform “Accelerator Pedal Released Position Learning”.
2. Perform “Throttle Valve Closed Position Learning”.
3. Start engine and warm it up to normal operating temperature.
4. Turn ignition switch “OFF” and wait at least 10 seconds.
5. Conform that accelerator pedal is fully released, turn ignition switch “ON” and wait 3
seconds.
6. Repeat the following (steps 7a, 7b) procedures quickly five times within 5 seconds.
7a. Fully depress the accelerator pedal (HARD)
7b. Fully release the accelerator pedal.
8. Wait 7 seconds, fully depress the accelerator pedal and keep it for approx. 20 seconds
until the Check Engine Light (CEL) stops blinking and turned ON.
9. Fully release the accelerator pedal within 3 seconds after the CEL is ON.
10. Start engine and let it idle.
11. Wait 20 seconds.
12. Rev up the engine two or three times and make sure the idle speed and ignition timing
are within the specifications.

 

try cleaning the butterfly in the throttle body, worked for me...

 

Will so not. Thanks. I did that over the weekend and it worked.

 

when welding underneath a car you have to worry about the grounds. mess one of them up and you will have your car searching for ground and it can cause alot of problems.