GM Astra 2.0 diesel EGT faults (UK)

Hi there, as the title says im in the UK, but im hoping that you guys have Astras in the States. Basically i have a 2013 GM Astra 2.0 diesel engine that has registered 2 DTCs referring to Exhaust Gas Temperature. They are P2084 and P2479 high exhaust temp codes. The car has an 02 sensor, then a temp sensor pre cat and then temp sensor post cat. My verus will only show me 1 data pid and it is for EGT Temp sensor 1 voltage. Problem is that if i unplug either of the temp sensors then a code saying temp sensor 2 or 3 appears? If i unplug the o2 sensor then it brings up an 02 fault but no temp sensor 1 fault. The data pid whether the car is hot or cold will show 0.04 volts to 0.06 volts. I have unplugged both temp sensors and they have a good 5v ref and a good earth. If i check both sensors with my power probe then as they warm up the voltages rise and they read the same as each other. With no data pid to rely on what options do i have? I have carried out an exhaust back pressure test and i dont have a plugged exhaust. The car isnt down on power it simply brouht on the check engine light. Do i scope both sensors and road test until i see a glitch on either sensor? I have no access to a wiring diagram so i cant see if the sensors share a common earth etc. Any suggestions welcomed, thanks guys

Dave

Hey Mossy, welcome to the forums! We actually did get an Astra for a few years, as a Saturn. No diesel engine available, of course.

Just doing some quick Googling, it looks like both codes related to the Bank 1 Sensor 2 sensor. Not sure exactly which one that points to, but I'd guess that to be the one in front of the cat? We'll be able to tell better later on.

Having little scan data to work with sucks, but we can still get by! If you clear the codes, how quickly do they come back? Instantly, or after a test drive? Trying to determine if this is an intermittent problem, or a hard fault.

My first thought is to take your best guess at which sensor is B1S2, disconnect it, and short across the pins. You should instantly get a fault code, hopefully something like 'EGT Signal Low Bank 1 Sensor 2'. Hopefully it codes, 'cause that'll verify the wiring, and that we've got the correct sensor identified.

Is swapping the EGT sensors a possibility? Just thinking about intermittent failures, and how we can make the fault come to us, if at all possible.

So with them plugged in and back probed you can see the reference voltage rise towards five as it warms up?

Out of curiosity, have you cleared the code and had it come back? Did it come back straight away or after a run? I'm wondering if there is a mechanical problem causing an actual overheat.


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You will have aleady found this this and this

Not exactly useful

Thanks alot for the reply Tyler. I unplugged each sensor ine at a time to register a code and like i said in my OP the aftercat temp sensor registered a sensor 3 fault, the pre cat sensor registered a sensor 2 fault and then i was only left with the 02 sensor which i thought perhaphs had an EGT sensor intergrated into to it but that came up with a 02 code.

After i had completed all of my checks i cleared all codes and ran the engine and no codes logged. I then took the vehicle for about a 10 mile road test and got the engine well upto temperature whilst giving various load. The car was certainly not under power at any time and the coolant temp was fine. After road test still no faults. I kept my live data going on road test and the EGT sensor 1 voltage did not change from the 0.04-0.06 it had given me from the start.

So its certainly not a hard fault. Swapping the sensors over did cross my mind as well and i think it is possible to do yes.

After the codes would not return following my road test i gave the car back to him to use for a few days/week to see if the check engine light comes back on.

Thanks for your reply as well Matt. Yes i had both sensors back probed and i was watching the voltage rise on both circuits as the engine got warmer. They were reading near identical as well with the post car sensor being more delayed as i would expect.

I have replied to Tylers post regarding the road test/hard fault comment but after a really good run the engine was not over heating on me no

Mossy1985 wrote: After i had completed all of my checks i cleared all codes and ran the engine and no codes logged. I then took the vehicle for about a 10 mile road test and got the engine well upto temperature whilst giving various load. The car was certainly not under power at any time and the coolant temp was fine. After road test still no faults. I kept my live data going on road test and the EGT sensor 1 voltage did not change from the 0.04-0.06 it had given me from the start.

So its certainly not a hard fault. Swapping the sensors over did cross my mind as well and i think it is possible to do yes.

After the codes would not return following my road test i gave the car back to him to use for a few days/week to see if the check engine light comes back on.

Sounds like a plan! Intermittent faults are the worst. All of your testing was good, FYI, just happens that it wasn't acting up at the time. Hopefully the owner is understanding about such things.

Sorry my reply doubled up your 1st post a bit. I misread some of it. Do you have an actual code description for both codes? Is it just overheat condition listed for both codes and doesn't specify a particular sensor? We don't get them here either so I can't find much.


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Its ok Matt no worries. I will need to get the description off my verus and report back as i cant remember them both off the top of my head however one of the descriptions was - high temperature, high temperature. So going off that code i assume it saw a high temperature lol

Yea he is a mate of mine so he has no issues taking it away to see if it faults again. Just frustrating that i couldnt get it to act up plus that i had such poor pid coverage. Vauxhall (as GM are known over here) generally tend to have decent pid coverage from snap on, but not on this one unfortunately.

I'm just wondering if it's indicating a fault such as implausible signal, or recording an actual overheat condition caused by over fuelling or similar.


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Had chance to look at my fault code descriptions today Matt.
So as follows

P2479 - Exhaust Gas Temperature sensor 1 - High Temperature High Temperature - History

P2084 - Exhaust Gas Temperature Sensor 2 - Performance - History

And then like i say, with both temp sensors unplugged it was logging a sensor 2 and sensor 3 fault code. The 02 sensor is a 5 wire design on this car, however the Verus doesnt have a wiring diagram built in and i couldnt lay my hands on a diagram from elsewhere (very hard in the UK). So unless the 02 sensor has an EGT sensor intergrated into it im really not sure why its giving me a sensor 3 code?