Hey guys!
My 06 Pontiac Torrent was throwing a P404 code, which is EGR valve is stuck open. So I went to the wreckers and grabbed one off an 08 Pontiac Torrent and tested it out so made sure it was all good. However after installing the new(used) one I was thrown a P1404 code which is EGR valve closed.
Is there anything that would cause the EGR to throw both of these codes. I know the last one was busted because I had some hesitation on acceleration, once I changed it out the acceleration has been fine.
Wondering if maybe it’s the wiring connection that might be causing it. If you guys have any ideas, let me know.
Thanks in advance guys!
Both codes P0404 and P1404 are the same code.
There’s a problem with the EGR Circuit Performance.
Electrical.
The difference is, the P1404 code is a GM specific code. Where the P0404 code is a generic code. Applies to all vehicles.
Tester
No experience w/that engine, but on my Corolla the EGR system is configured with a thermistor (egr temperature sensor). That’s how the ECM tells if the EGR is actually open, closed, or somewhere in between. If closed even though the ECM commands it to be open or partially open, no hot exhaust gas reaches the thermistor. So the thermistor registers cooler than what the ECM thinks it should, and an EGR code is thrown. In other words the problem could be either the EGR valve, the gadgets (often vacuum switching valves) that operate the EGR valve under computer command, or the temperature sensor circuit. Since you know the egr valve works, it must be one of the latter two that’s the problem. It may be possible using a scan tool to command the egr to open and close at will. If so then you can just look at it. If it opens and closes by scan tool command, then the problem is most likely the thermistor circuit.
Yea that makes sense. I am not sure about my Torrent, I don’t see any other sensors connected near the EGR, or on feed down into the intake. I am thinking it would be a computer command issue.
Would the computer need to be replaced if that’s the issue? Or is it just simple as recalibration?
These are the things that can cause those codes.
https://www.obd-codes.com/p0404
Tester
A computer problem seems unlikely and is at the end of the suspect list, not where to start. My basic test for the EGR valve on both my Ford truck and my Corolla is this: Engine warm, at idle. Connect hand held vacuum pump to egr valve vacuum input. If engine stalls when 20 in vacuum is applied, EGR valve passes this test. That’s where I’d start.
George.
Both the EGR valve systems in your vehicles are back pressure induced EGR systems.
How do you apply the back pressure to the EGR valves before the vacuum is applied to the EGR valves?
Tester
You don’t need to look on the internet George.
You should know this?
Tester
If engine stalls when 20 in vacuum is applied, EGR valve passes the test. That’s how I do it on both my current vehicles, and on my prior Rabbit. The engine always stalled on my Corolla and Rabbit, but not always on my truck. Replacing the egr valve fixed it.
Well I think in this instance I will likely just take it into a mechanic. Don’t have the vac tools I would need, and I am sure they would be able to diagnose it in no time. If it’s something simple I can usually fix it myself, but diagnostics is not my forte.
EGR systems on modern obd ii vehicles are complicated, so if replacing the valve didn’t fix it, your idea to take it to the shop has a lot of merit.
Thanks to you both for all the info though, definitely gives me a baseline to go off of. I’ve got the engine mechanics down as my Father was a heavy duty mechanic and used to help him in his shop, but trickle down issues are something I would have to go to a mechanic for because I would just replace everything that seemed an issue
I think on more modern engines like yours instead of a thermistor to determine if the valve has opened upon command, instead there’s a positioning sensor that actually measures whether it moves or not. The replace stuff method used to work pretty good on older designs, but with modern engines you can quickly run out of money replacing stuff on a guess. Easy to run out of money before running out of guesses.
It is a possibility that the used EGR valve is no good. There is a service bulletin to replace Delphi EGR valves with a Siemens replacement valve with a new connector and software update. The replacement kit is available from Rock Auto, the software update will need to be performed at a repair shop with access to GM software updates.
You also don’t have a 1973 Ford, the EGR valve on your engine is not vacuum controlled. Unfortunately to perform EGR actuator tests you will need a professional scan tool.
Awesome thanks guys! Truly appreciate the feedback. I actually need to to order some sway bar bushings from rock auto, so the 60 bucks for a new EGR might not be that bad. My girlfriend works at a salvage yard, so I get used parts at half cost. So was worth pulling a used EGR for the 5 bucks it cost me for the pipe and valve.
That is indeed a good price. Last time I replaced the EGR on my truck – presumably a more simple design than yours – the part alone cost $100.