Car = 1.2 12v polo 2003 9n

car not starting after vag com used.

hi, my mates car has been cutting out while idling, so we plugged vag com in to find any faults, we found engine 1. coolant temp sensor 2. manifold barometric pressure sensor.

we unpluged the vag com found the temp sensor and rang for a quote, i started the car to show my friend the noise of power steering (so hes not confused with the rad fan noise) but when he came to leave the car did no start, lots of crank but no starting,

RAC came and did a few tests pluged a comp in, its getting a spark, fuel = spark plugs wer wet (cleaned put back), compression ok,

the rac guy said its prob timimg (said common fault is chains skip a tooth) but that would be a massive coincidence.

could this be something to do with the vag com ? any ideas or similar things happen to you?

feel like a massive knob now he came with a half running car and left on tow...

unplugged batt for roughly 10mins and tried again, still no luck

I got a different engine but had the same fault of non start/ cutting out etc... In the end it turned out to be the coolant temp sensor, for £8 I recommend doing that first... Make sure you bleed it after aswell

I got a different engine but had the same fault of non start/ cutting out etc... In the end it turned out to be the coolant temp sensor, for £8 I recommend doing that first... Make sure you bleed it after aswell

thank will butg cant see that not letting the car start? it cut out before but always started back up?

Maybe only posting in one section would be a good start =\ and yes temp sensors can cause this, its a diagnosed fault. Check the wiring or replace.

And I've never known a timing chain skip a tooth! Also being 2003 not 1963 I'm doubtful it even has one..... Though I could be wrong.

Maybe only posting in one section would be a good start =\ and yes temp sensors can cause this, its a diagnosed fault. Check the wiring or replace.

And I've never known a timing chain skip a tooth! Also being 2003 not 1963 I'm doubtful it even has one..... Though I could be wrong.

What Rac guy said, one comon fault noted on here is that 1.2 12v 9ns chain tensioner fails around 50k so it's very possible.

Was running fine. Not touched anything apart from checking fault codes?

Posted in two areas cus it's engine and or electrical prob.

Just reading the fault codes will not have affected the ECU's settings, unless you tried to alter any of the basic settings, so it is just a coincidence that it will not start now, as you stated the plugs are "wet" and your getting a good spark, so the only thing stopping it running is the timing of the spark and the fuel

Just reading the fault codes will not have affected the ECU's settings, unless you tried to alter any of the basic settings, so it is just a coincidence that it will not start now, as you stated the plugs are "wet" and your getting a good spark, so the only thing stopping it running is the timing of the spark and the fuel

Yeah it did start after vag com, just seems like a big coincidence that it happened after checking the codes. Really hope it's not timing chaIn tensioner throughing timing out, can imagen that's a big job

Just reading the fault codes will not have affected the ECU's settings, unless you tried to alter any of the basic settings, so it is just a coincidence that it will not start now, as you stated the plugs are "wet" and your getting a good spark, so the only thing stopping it running is the timing of the spark and the fuel

Yeah it did start after vag com, just seems like a big coincidence that it happened after checking the codes. Really hope it's not timing chaIn tensioner throughing timing out, can imagen that's a big job

It is just a coincidence, the reading of the codes will NOT have affected the car

Well all I'm saying is I recon it will be the coolant temp sensor, it's a common fault with VW's and Peugeots causing non start running issues etc.... Think u'll be suprised when it fixes it

Edited 23 June, 201214 yr by matt01

Well all I'm saying is I recon it will be the coolant temp sensor, it's a common fault with VW's and Peugeots causing non start running issues etc.... Think u'll be suprised when it fixes it

On these cars the engine management systems is quite basic, if a sensor fails, the ecu will fall back onto a stored basic set of values and still allow the engine to run, unless the sensor is like the cam or crank position

Well all I'm saying is I recon it will be the coolant temp sensor, it's a common fault with VW's and Peugeots causing non start running issues etc.... Think u'll be suprised when it fixes it

On these cars the engine management systems is quite basic, if a sensor fails, the ecu will fall back onto a stored basic set of values and still allow the engine to run, unless the sensor is like the cam or crank position

My bad then. I work for Peugeot maybe they should use these sorts of ECU's that fall back on set parameters... We still change ones on 61 plate 308 + RCZ's

Well all I'm saying is I recon it will be the coolant temp sensor, it's a common fault with VW's and Peugeots causing non start running issues etc.... Think u'll be suprised when it fixes it

On these cars the engine management systems is quite basic, if a sensor fails, the ecu will fall back onto a stored basic set of values and still allow the engine to run, unless the sensor is like the cam or crank position

My bad then. I work for Peugeot maybe they should use these sorts of ECU's that fall back on set parameters... We still change ones on 61 plate 308 + RCZ's

On the newer cars you you are working on, the parameters for sensors etc have changed, if any sensor fails the ECU reverts to total protection mode, and will restrict the rpm to >3000 rpm put up the "fail light" but the OP has a basic early edition of engine manegment sytem and it will "fail safe" to it's stored values

Could be a dumb question but is there fuel in the tank? The easiest things sometimes get over looked like fuses etc...

Could be a dumb question but is there fuel in the tank? The easiest things sometimes get over looked like fuses etc...

Yes half a rank of fuel. Checked fuses ( it's getting a spark, and fuel)

could the Ecu change the timing? Cus cus it looks to me to be a timing prob.

And I've never known a timing chain skip a tooth! Also being 2003 not 1963 I'm doubtful it even has one..... Though I could be wrong.

It's quite common on these, the newer Polo's used a timing chain, rather than a belt. Same as the Corsa, ever heard a rattely sounding Corsa?..

Vag-com won't have affected starting, like it's been said, you've got fuel and spark, now it's timing..

Temp sensor could be so far failed that it's chucking in too much fuel, or too little, possibly. Might help if you hold the throttle wide open to try and clear some of the fuel out..

I'd say replace the temp sensor, it's common on all of them, and for the cost of it, it needs replaced anyway..

Does it log any codes once it's been tried to start?

And I've never known a timing chain skip a tooth! Also being 2003 not 1963 I'm doubtful it even has one..... Though I could be wrong.

It's quite common on these, the newer Polo's used a timing chain, rather than a belt. Same as the Corsa, ever heard a rattely sounding Corsa?..

Vag-com won't have affected starting, like it's been said, you've got fuel and spark, now it's timing..

Temp sensor could be so far failed that it's chucking in too much fuel, or too little, possibly. Might help if you hold the throttle wide open to try and clear some of the fuel out..

I'd say replace the temp sensor, it's common on all of them, and for the cost of it, it needs replaced anyway..

Does it log any codes once it's been tried to start?

No it doesn't log anything, yeah we will try the sensor and see from there cheers,

Was it a genuine vagcom? Or eBay cheap?

As you crank it do any lights come on?

an ebay vag com, basic functions used lots before on other cars with no probs. and a rac one.

yeah a few lights come on oil one of them. but it has oil

an ebay vag com, basic functions used lots before on other cars with no probs. and a rac one.

yeah a few lights come on oil one of them. but it has oil

From what I remember (as it was my RAC membership that got him towed home) EPC light, Engine Management light and oil pressure light were on when cranking (Oil pressure was flashing and beeping)

Also tried full throttle while cranking and this didn't make a difference.

made sure battery was fully charged and tried jumping it from my Derv Ibiza but that didn't work either.

Does seem timing related to me.

May fried the ecu? Heard of eBay coms doing it before

May fried the ecu? Heard of eBay coms doing it before

if it fried ECU, then surely it wouldn't spark, or pump fuel?

Good point ignore me