Polo Engine Management Light

Nov 20, 2006 2 Replies

Hi all.



Question for any VW officionados.



My wife's got a 52 plate Polo 1.2. 3 cylinder 65PS version.



She's had some problems with the engine mangement light coming on. The=20 last time it happened was because of a coilpack failure. This time, she=20 called the RAC/AA out first time. They said it was a "Spurious signal=20 from the coolant temperature sensor".



They reset the alarm, but 2 weeks later it's back.



She took it to the local VW Stealer, and they hooked it up to read the=20 fault codes. This time it was...


17511 P1103 035 O2 Sensor Heater Circ. Bank 1 Sensor 1. Performance too=20 low, sporadic


16500 P0116 035 Engine Coolant Temperature Circuit G62 Implausible=20 signal, sporadic.



When the MIL first came on, I guessed it was an O2 sensor problem, and=20 sure enough, there's one up there.



The questions are...


1) Is this a common problem on 1.2 Polos?


2) As an electronic engineer, when 2 sensors come up as "sporadic" and=20 "implausible", I start to think "bad connection, or serious quantities=20 of noise". Would a failing coil pack squirting HT/HV into the ECU cause=20 these problems?


3) If they really *are* the O2 and coolant temperature problems, how=20 hard are they to fit? With 2 hours diagnostics, they said it would be ~
100 for the coolant sensor. I'm assuming it's a standard "screw into the=20 jacket" job? Similarly, how much would an O2 sensor set us back?


4) Anyone know if these 2 sensors share a multiplug somewhere in the=20 engine bay?



I don't want to take the car to the dealer, have them swap random bits=20 at =A345/hour, for them to say "No idea!"



Any ideas?



Thanks.



Pete.


They're both fair;y easy to fit, eurocarparts sell them, if the cts is playing up then it can confuse the ecu, so the other fault might be caused by that.

Not related to a Polo, but on the Mk4 Golf's, the coolant temperature is a very common problem. I replaced the one on the my Golf, took 5 mins to fit (held in with a plastic clip) and cost around £27.

Again, I had to replace two front O2 sensors on my Golf, £83 +vat each I think. Fitting wise, they screw into the exhaust and there is a connector block under the car. Again, these comments are for a Golf, would have thought the fitting would be quite similar between models though.

May be worth getting the fault codes cleared and see if / when they come back. I bought a vag-com serial cable from ebay for around £20 inc postage. Download the vag-com software from the internet and use on a laptop. Saves been stung by the stealers charging you for a diagnostic scan.

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