Justin-T

My 2015 A4 is giving an error corresponding to the fuel temperature sensor. My mechanic says I'll have to replace the entire fuel pump assembly to do so, is this correct? I'm seeing other models where this sensor is easily accessible, but the lack of anyone selling a sensor on its own for this model A4 suggests he's right. This is basically a last resort in trying to avoid such a costly fix for what seems like it should be much easier & cheaper fix than it (apparently) is... Car does not appear to be burning gas at a different rate, or running rough.

SMac770

Fuel temp sensor? What engine is this? CAE 2.0T? CPM 2.0T flex fuel? If it's the flex fuel, I wonder if there's a fuel temp sensor integrated into the fuel quality sensor (determines the current gas/ethanol ratio coming from the in-tank pump). As for it being on the in-tank pump, I have no idea how it would pass any measurement back to the ECM. My CAE has a fuel temp measuring value, but I have no reason to believe it's a real measurement, and not just some modeled value. I have exhaust temp measuring values, but there's no exhaust temp sensor on an EA888, it's just modeled values.

What is your exact complete DTC text?

Justin-T

Thanks for the reply, not certain on the engine, but pretty sure its not flex fuel. Don't know the complete text, this was reported by my mechanic after he'd checked via the scanner. I'd have to ask him to check it again to get that.

SMac770

When you look under the hood, is the intake manifold hanging off the right side of the cylinder head made of plastic or metal? There's a white sticker on the front of the upper timing cover; does it say CAE or CPM? As for the code/DTC text, yeah, you'll need the scan tool to look at that.

tonyvu

hey justin did you ever end up fixing the issue? was the cod p2024,p2025,p2026??

Justin-T

I'm 99% sure those were the codes. My mechanic recommended taking the car to a dealer for a more advanced diagnostic, because he'd heard that sometimes these codes can get thrown by a timing chain issue, making changing the fuel pump a complete waste of money. That turned out to be correct, it was in fact part of the timing chain mechanism - don't know what its called, but you can see it in the guy's hand in this video at 13:58, it was one of the teeth in the small, central circular connecting ring. My mechanic mentioned it's a bad design and they're notorious for getting damaged. There was wear in several places and one of the teeth had broken off, stuck between this ring and (I assume) a matching ring inside the engine. So it basically works, but it throws the timing off just enough that you get weird codes.

It took them almost a week to fix it and cost me $2700. Which was a bad enough, but then a few months later the Audi was totaled after being rear-ended by an uninsured Dodge Ram driver on I-95 in Delaware... Because we don't have the car any more we disposed of the records so I can't check the report I got from the dealer. Good luck!

Justin-T

Just remembered my mechanic sent me a photo.

SMac770

P202x codes are EVAP fuel vapor temp related. Nothing to do with the engine at all. And if the original issue came back as timing related, then the original errors were about fuel pressure, not fuel temperature.

Something seems odd about that explanation, regardless. If the crank bolt is tight, that vibration damper is not slipping. If the crank bolt is messed with, then things can get put back incorrectly if one is not very attentive to the key markings. There's also two different torque specs, depending on if it's an older 8.8 crank bolt or newer 10.9 crank bolt.

That last picture is very interesting. But again, hard to say if that damage would be there if all was always done right. Sucks to hear about the eventual outcome though. I wonder if you can claim the value of recent expensive work, or your stuck, at least from the insurance's concern, to just the "car value".

Justin-T

You are correct about the code number's official meaning, but I had the CE light on for months, with no issues whatsoever with the engine that I could tell, but as soon as the timing chain work was done (mechanic actually just cleaned it up, removed the busted pieces and put it back with a new chain) the error codes were no longer being thrown. Car ran fine after that until the crash. The VW dealer indicated the issue was timing chain related also, so despite the code's listing, the problem was not actually related to the fuel temp sensor in any way.

SMac770

That's my point. The original issue you had was not a fuel temp sensor issue. The intelligent guess is it was high pressure rail fuel pressure related, such as P2177, P2178, P2187, P2188, P2293, P2294, or P2295. As that will be impacted by timing issues. The EVAP vapor temp sensor is in the back of the car, at the leak detection module. Since the EVAP codes will set the MIL, and they could not have been fixed by timing, then they must not have been the codes in the first place. It was fuel pressure codes, and they got fixed when the timing was fixed. Is the most logical guess without the actual original DTC scan log.

But on the vibration damper, you never had any work done on the engine front end prior to that event? Chains or pistons or any of that? Would be worrisome if that damage was from a factory installation. Is expected from field work if they aren't careful.

That video you linked is really well done. That special tool was introduced after my workshop manual copy was made, interesting to see it in use. Definitely more reliable than the old process of "just get lucky".