Coolant Sensor

[m50yre]

Hi All,

Newly registered on here but i have learnt loads from very useful info posted on here before registering.

I have a 95 Coupe 2.0e ABK - it has the common rough running problem when idling and also the head gasket has gone but i need some help with a few other things.

When i got the car neither the oil temp or coolant temp guages moved barely off the start position, the car shortly after this failed its MOT on a few things including emmisions. Fixed the usual things like flexy hoses, sticking calipers etc but after some investigations i decided to change the coolant temp sensor / sender and the oil temp sensor / sender. Went to Audi and these are the parts they sold me;

026 906 161 - Switch
025 906 041A - Sensor
053 919 501A - Temp Sender

Now i managed to replace the last two but im stumped if i can find the first one on my car. I got a copy of the exploded view from Audi's ETKA system (illustration 919-60) in which this mystery sensor is No7. The other sensors are No's 22 & 23. It looks as if the housing where my two sensors are in could have an alternative housing, perhaps for a different year/model/ variant and thats where the other sensors (No's 3 & 7) fit in?

Also they gave me no oil sensors to fit. The oil temp guage does come of its start position but only a very small amount. The coolant one works fine now but doesnt move more than maybe a quarter of the way up the scale, i suppose with the head gasket problem the engine doesnt get to full operating temperature?

I have also replaced relay No.30 which has helped.

Any help on the mystery sensor is very much appreciated, sorry for the long first post!

Matt

[scotty33]

The part you cant find 026 906 161, is as you say, a part for the alternative water manifold, that setup is the 16v version so they have sold you a part you cannot use.

My guess is you think you needed 049 919 563B which is an oil temp sender, which is installed into the oil filter housing.
I say 'you think you needed', because most 80's with the gauges, have an oil temp reading that barely moves under normal use, so I doubt a new sender will have much/any effect?

[m50yre]

Hi

Thanks for taking the time to reply. I wasnt aware that it was normal for the 80's oil temp to hardly move as this is my first one, id already ordered that sensor so we'll see if it makes any difference.

Any tips for the head gasket when i do it? The manifolds look like a bit of a mare to get off?

Matt

[m50yre]

Finally managed to hook this up to VAGCOM, results below, any thoughts?

I've sorted the airbag issue, that was me taking out the dash that caused that.

VAG-COM Version: Release 311.2-N

Chassis Type: 8C - Audi 80 B4
Scan: 01,02,03,08,15,26

Address 01 -------------------------------------------------------
Controller: 039 906 024 D
Component: DIGIFANT 1.75 1714
4 Faults Found:
00513 - Engine Speed Sensor (G28)
03-00 - No Signal
17978 - Engine Start Blocked by Immobilizer
P1570 - 35-00 - -
00525 - Oxygen Sensor (G39)
03-10 - No Signal - Intermittent
00522 - Engine Coolant Temperature Sensor (G62)
27-10 - Implausible Signal - Intermittent
Readiness: N/A
Address 03 -------------------------------------------------------
Controller: 4A0 907 379 A
Component: Bremsen-Elektronik
Coding: 0265100056
Shop #: BB 33837
No fault code found.
Address 15 -------------------------------------------------------
Controller: 8A0 959 655
Component: Airbag IV AUDI D00
Coding: 00766
Shop #: WSC 06313
2 Faults Found:
00532 - Supply Voltage B+
07-10 - Signal to Low - Intermittent
01025 - Trigger for On Board Diagnostic Lamp: Malfunction
31-10 - Open or Short to Ground - Intermittent
End -------------------------------------------------------

[scotty33]

Hi

Thanks for taking the time to reply. I wasnt aware that it was normal for the 80's oil temp to hardly move as this is my first one, id already ordered that sensor so we'll see if it makes any difference.

Any tips for the head gasket when i do it? The manifolds look like a bit of a mare to get off?

Matt


I had the head off a 8v passat once, left the manifolds on the head! The engine install in the 80 is different, may be easier to get at the manifold(s) bolts/nuts.

[scotty33]

Finally managed to hook this up to VAGCOM, results below, any thoughts?

I've sorted the airbag issue, that was me taking out the dash that caused that.

VAG-COM Version: Release 311.2-N

Chassis Type: 8C - Audi 80 B4
Scan: 01,02,03,08,15,26

Address 01 -------------------------------------------------------
Controller: 039 906 024 D
Component: DIGIFANT 1.75 1714
4 Faults Found:
00513 - Engine Speed Sensor (G28)
03-00 - No Signal
17978 - Engine Start Blocked by Immobilizer
P1570 - 35-00 - -
00525 - Oxygen Sensor (G39)
03-10 - No Signal - Intermittent
00522 - Engine Coolant Temperature Sensor (G62)
27-10 - Implausible Signal - Intermittent
Readiness: N/A
Address 03 -------------------------------------------------------
Controller: 4A0 907 379 A
Component: Bremsen-Elektronik
Coding: 0265100056
Shop #: BB 33837
No fault code found.
Address 15 -------------------------------------------------------
Controller: 8A0 959 655
Component: Airbag IV AUDI D00
Coding: 00766
Shop #: WSC 06313
2 Faults Found:
00532 - Supply Voltage B+
07-10 - Signal to Low - Intermittent
01025 - Trigger for On Board Diagnostic Lamp: Malfunction
31-10 - Open or Short to Ground - Intermittent
End -------------------------------------------------------


probably best to do the bits you have got, clear codes, then rescan and go from there.

g62 I think you have, speed sensor sometimes comes up if the engine is not running when scanned? Would not run if it is failed!
immobiliser glitch is not uncommon, if the reader coil is slow to read the transponder in the key.
lambda could be a problem, but they don't last forever..

[m50yre]

Ok cheers, i've just cleared the codes so i'll run it home and check tomorrow to see what it comes up with. Any idea where the lambda goes into the exhaust? Presumably theres a wire back up to a multiplug or something in the engine bay?

[m50yre]

So the codes have come back. I'll get a new lambda and see if that helps. Any ideas what could cause this implausible signal from the coolant sensor? Which one will it be the blue or greyish / white one?

Matt

[m50yre]

So I fitted the new lambda today but the code never went away. I cleared them and it came back. I tried all the connections again the ran vagcom with the engine running,same thing. Fiddled around for a while by this time the car was up to temp and I went into the controller for the engine then wiped the codes from there and now all of them are gone? Could it be that the lambda and coolant sensor don't give out signals until a certain temp? All previous reads were done with the engine off and cold?

[scotty33]

The engine runs from various sensors and a table of fixed values stored in the ECU during warm up this is open loop control. When the temp reaches I think 80 deg C at the ECU temp sender G62. The ECU starts using the Lambda sensor to control mixture at part throttle/idle - closed loop control. (at wide open throttle it still runs open loop)

Maybe the ECU needs to see a healthy lambda working before it will allow the code to clear?
If you still have a problem it could be a wiring issue?

[m50yre]

Thanks for clearing that up, sounds like i should be OK now, no codes present last time i checked. It drove fine today but then it never really drove badly, without VAGCOM i probably wouldnt have changed the lambda.

On a side note the connection between the downpipe and the cat i noticed was blowing. The flange on the downpipe on the upper most hole is missing, so ive sourced another downpipe. The cat looks fairly old and has a pretty weak looking flange too so may aswell change that too, any recommendations for where to get a decent one?

After this hopefully that will be all the repairs for a while, typical they all come in winter!

[scotty33]

I tend to think its best to stick with what you have for as long as possible exhaust wise. The Cat should be stainless so any deterioration should be slow. The whole syatem although it rusts is also a low grade of stainless I think. Far better quality than anything you will buy cheaply.

Cat wise I have in the past used one from fuelparts which was cheap, but had to have some of the mountings welded on. More importantly it was a fir bit smaller than the old one so probably a bit restrictive. It lasted approx 3 years before melting, but not sure if that was due to another running problem?