temp sensor abf

I recently replaced the water temp sensor in my abf engine as I put in new coolant. I now have a red light flashing but temp seems normal in fact running a bit cooler since the new coolant us added… any ideas? I'm going to try the origin temp switch again just in case it's a faulty switch.

Just switched the old sensor back and the same issue… the light comes on on ignition and goes off after a few mins running it comes on again and stays flashing.


I checked the earth and it seems intact, the only other possible problem i can see is the cap on the expansion bottle burps up water when the ignition is turned off so it looks as if a new cap is needed - could this be an issue if its not keeping the water pressure?

status update now the temp sensor is showing max temp as well as flashing light, engine seems fine as I said the only thing Ive done is flush coolant and replace the water temp sensor. Old sensor is back in and its reading max temp after a few mins of running.

Do these temp sensors need to be programmed with a vagcom? When are the typical error codes for temp sensor?

 

Hi I just had a similar problem on my car not running an Abu though. But if you go to your fuse box drop it down there is a relay on top for the coolant level. Pull it out and check it for corrosion as mine had loads clean it all off including the clips in the loom plug and all was back to normal. I found this info on a thread by rub Johny and it sorted my problem out. I think it was relay 43 or 42 but my car is a 88  gti cabriolet.  good luck.  

ill give that a go in the morning, i went through every fuse on the board this afternoon and they all seemed fine, whats bugging me is when i put back the old switch the problem continued which is not logical since this problem didnt exist prior to the new sensor going in.

Hi also I meant to say. Check all your earths also,fuse box engine bay starter motor etc I have just shipped my car down here to New Zealand and all was good when it went into the container.but it was an electrical mess when it came out.
Good luck mate.

Yeah I suspect its an earth issue alright as my battery has been going flat recently and its taking a charge in just a few hours but where to start with that… I recently took out the door light switches as they are not working im waiting for a new set so right now i have both wires taped up.

I checked the earths on the same side of the head as the coolant sensor and both seem intact and making good connections.

I still think this problem could be diagnosed with the vagcom or at least point some direction as to where to start.

Just checked over the relays no joy, the temp sensor still dosent seem to be sending the signal to the dash.

Here is a pic of the new sensor in with the earth.


 

thats the ecu temp sensor, the dash sensor is the small black one to the top right

your wiring doesnt look very clever, strip that tape off and make sure its all good underneath.

and the earth ringss should go to a bolt near the rear corner of the head not on the main loom retainer bracket bolts (though it probably wont be causing your issue)

Ok so the dash sensor is the one with the red circle on the right?

I have another sensor thats not connected to any wiring behind the black cable (yellow circle) do you know what this controls?

I might replace the dash sensor as it may have become upset when I fitted the new ECU sensor, do you have a part number on the dash sensor?



I had the tape off the wires at the weekend there were a few cracks on the wiring covers so I suspect this was used to seal them up, (dosent look to bad underneath)

As for the earth do you have a pic of where these should be connected?

I got these part numbers from vagcat can you map which switch goes where from this? from what i can make out the following sensors seem to correspond;

4. Temp sender 0-150C M10X1 1 pin white - 1H0919563

7. Temp sender M10X1 2 pin white (ecu?) - 026906161

9. Temp sender 0-125C M10X1 1 pin black (dash sender?) - 049919501






Thanks in advance.

is the yellow circle on the distributor? if so you need to sort that as its loosing you power! if its a 3 pin plug with a black, brown and blue/white thats the speedo sender for the mk3 dash so you can ignore

the red circle is your dash sender, its the 049919501 part number. NLA from VW but if you ebay that number and the older revision 027919501 sometimes you can get NOS genuine senders for cheap.

the wire looks a bit kinked, maybe its split at the spade crimp so check that as well

I dont have a pic of the earth point to hand, but its one of the rearmost threaded holes in the side. you may find the wires wont reach anyway, just so long as they have a good connection to earth where they are then its all good

OK i have the sensors sorted now reading water temp from the dash without any red lights or off the scale readings.

The problem I have now is idling at 1500rpm… it will occasionally drop to 1000 when its warmed up but once its driving its sitting around 1500 when idle, even thru the gears its reluctant to drop below 2000rpm.

I replaced the washer on the ISV but its still leaking air when warm. When I disconnect the ISV it drops to 1000rpm but is there any sure way to say its 100% ISV ? Its hardly a cheap part and I want to be sure thats the problem before buying one.


Its buzzing away when the ignition is engaged, I tried washing it out but no difference…
 

mine is almost silent, you have to touch it to know its working so if yours is loud this could be a clue. I went thru 3 isv before i foudn oen that my ecu was happy with. if you click the link in my sig theres a couple abf pdf covering the setup of the idle switch/throttle stop position, plus the procedure for matching a the tb and isv to the ecu both worth a read anyway!