High revs

[audia4lyn]

Can anyone please help
Had my car for a week now, A4 2.5TDI TipAuto 2000. Sometimes when I start her up it revs at about 1500 to 2000rpm with a single beep, after a minute revs drop to normal and then she’s fine it dose this if the engine is already warm, has not done it from cold.
Thanks
Lyn

[sbt]

hi just solved the exact same problem on my a4 1.9 tdi its the coolant temp sensor change it for 20 quid from gfs not sure about 2.5 tdi but it took me 10 mins to replace

[audia4lyn]

Thanks sbt
Did yours beep once as well?

[sbt]

no there was no beep but mine is the 1.9 tdi pd what you described was the exact same symptoms as mine it never happend when cold only when warm it would rev to about 2000 to 3000 rpm for about 5 to ten seconds then fall back to normal revs it did not happen every time just 3 or 4 times a week i replaced the sensor 4 weeks ago and it as not happend since. these sensor are well known for failing nothing shows up on vag com it is sending the wrong message to the ecu and over fueling

[audia4lyn]

Thanks sbt

I will have a look at my temp sensor to see if it sorts mine out.
getting a haynes manual to find my way around these engines.

Thanks again, you've been a big help.
Lyn .:fing02:

[tbear911]

Hi Lynn,
I have had the same model as you for about a month now and it's started to do much the same as yours. Tickover on cold start is fine, but it will rise to about 1300 rpm when the engine is warm. Glow plug light goes out almost instantly on a cold start, but stays on for ages when starting if the engine is hot. Have you changed your sensor yet and did it work?
Regards,
Ted

[sbt]

hi ted forgot to mention my glow plug light used to stay on for about 10 seconds .again it as not happend since i changed the coolant temp sensor i suggest you change it i think you will be pleasently surprised a dodgy sender will cause all sorts of problems and for 20 quid and 10 mins work why not. let me know how you get on. remember do it when the engine is stone cold and have every thing to hand that way its out and in and you will not lose much coolant

[audia4lyn]

Sorry tbear911, did not see replay. No I have not changed the sensor as yet, been trying to obtain some kind of workshop manual to see where all these sensors are, I don’t know if you have got one, if so where did you get it from?. Or could you please tell me where the temperature sensor is. I think I need a MAF sensor as well (see latest post) but I know where that one is. Dose you 2.5tdi hold back a bit at high revs, if so it could be the maf.
Thanks tbear and sbt.
Lyn

[sbt]

change the cheapest part first that being the temp sensor the holding back you mention is all to do with fueling. you will not see any problems on your temp gauge because the sensor as a 4 pin connector 2 go to the gauge and 2 send info to the ecu . when it fails it could be telling the ecu your engine is cold when it is warm on the other hand it could be telling the ecu your engine is warm when in fact it is cold hence the holding back. another thing i noticed when i change my sensor was better mpg by about 4 to 5 mpg. as regards where to buy the sensor german swedish french or euro car parts 20 quid including vat

[audia4lyn]

Hi there sbt, where is the temp sensor,? is it on the top part of the rad

[sbt]

sorry not sure where it is on the 2.5 as i have said mine is a 1.9 on my car it is at the back of the engine near the top on the left hand side

[tbear911]

Good morning Lyn & SBT. Thanks for your responses. I guess that I will go for replacing the sensor. Don't have a manual, so like Lyn, I hope SBT can tell us where it is. Have a good day folks. Regards, Ted

[audia4lyn]

Hi there
I have just been to my local auto factors and all they could produce was a temperature transmitter which just pushed in somewhere, it had a blue top with two electrodes. this did not sound the same as sbt described so I left it there. I will have to find out more about this sensor, I might even go to my Audi dealer God forbid, and it’s a real pain without a workshop manual. :aargh4: Keep you posted.
Lyn