Repeated throttle pedal faults - ECU?

[Skoda-on-veg]

Hello everyone,

My first post on the forum and it's a cry for help – I know it's not the done thing but any advice would be very much appreciated. My local Skoda dealership are telling me I have a problem which could potentially cost well over £1000 and I'm beginning to sweat!

In some respects it seems quite similar to other problems forum members have had with their throttle pedals (e.g. http://briskoda.net/forums/topic/44084-throttle-sensor/page__p__1484339__hl__accelerator__fromsearch__1#entry1484339) but the renewal of the pedal hasn't fixed our problem.

In early January I got a very worried call from my girlfriend saying that the car (2002 Octavia 1.9 Tdi Elegance) wouldn't accelerate. The glow plug light was also flashing. She managed to crawl the car along at 20mph to our usual mechanic who used the error codes to diagnose a faulty throttle pedal and put a new pedal in. Job done – we hoped.

A few weeks later the same thing happened again – this time in the middle of a much longer journey. No crawling to the mechanic this time – we had to call out road rescue and have it towed back to the same garage which had replaced the pedal. They eventually traced the fault to different readings in the two cables running from the throttle pedal to the ECU (they said they are supposed to give the same reading?) and so they fused the two cables together to attempt to fix the problem with the warning that, if this didn't work, we would have to go to the Skoda dealership and have the ECU replaced.

Everything seems fine then, a month later, the same problem strikes once more. We take the car to our Skoda dealer. They carry out a diagnostic test and trace the error to the upper sensor on the throttle pedal once again. They now want to 'strip the car down' to check the throttle pedal wiring and have warned me that this will take three hours. If they don't find an obvious fault they have warned me that they will need to replace the ECU at £1000 plus.

Has anyone had similar issues and sorted the problem. Am I being taken for a mug by the dealership or are the prices and times they are quoting reasonable? If the worst comes to the worst and I have to replace the ECU would 2nd hand be a sensible option? I see there are plenty on the net but can they really be swapped from car to car without issues?

Any advice would be very welcome (although please bear in mind that I have very limited technical knowledge). I'll try to get the actual error code from the dealer tomorrow.

Thank you.

[moley]

A very similar problem occurred on my Sister in law's Seat Ibiza 1.9 sdi (Polo / Fabia running gear) about 4 years ago.

My brother calls me one Sunday, can you tow us home the car will only idle (limp mode), AA have been and reckoned it's the throttle pedal potentiometer that's at fault. They had no recovery on AA, so Out I went. The car started and ran for about 3 miles while I followed, when it stopped again I towed it home for the last 10 miles, got home and the car ran. A local independant garage also said throttle pedal and changed the part. All OK for a month or so, then identical problem, now they had AA recovery so back to the garage, but they couldn't get the fault to repeat. A month or so on same fault, now the Sister in Law doesn't trust the car, so back to the garage. In the meantime they locate a Fabia 1.2 HTP estate at the local Skoda dealer. The seat is back at the garage and they discover the possible fault. The ECU is mounted at the back of the engine bay and the rainwater from the screen hasn't been running out of the drain holes because thay are blocked, so it's been running over the lip and onto the ECU. They opened up the ECU and found it damp with some corroded terminals. They cleaned, dried and soldered some dodgy teminals and the car ran OK for the next 2 weeks before they PX'ed it for the Fabia.

[pauldazzle]

There's a guy down here in Sth Wales called Chris Hughes who repairs ECU's. He does a lot of work for the trade, & does a postal service too. His number is 07722288844, & if he can't repair it I doubt anyone can. He generally charges about £150.

Edited 13 March, 2011 by pauldazzle

[Skoda-on-veg]

A very similar problem occurred on my Sister in law's Seat Ibiza 1.9 sdi (Polo / Fabia running gear) about 4 years ago.

My brother calls me one Sunday, can you tow us home the car will only idle (limp mode), AA have been and reckoned it's the throttle pedal potentiometer that's at fault. They had no recovery on AA, so Out I went. The car started and ran for about 3 miles while I followed, when it stopped again I towed it home for the last 10 miles, got home and the car ran. A local independant garage also said throttle pedal and changed the part. All OK for a month or so, then identical problem, now they had AA recovery so back to the garage, but they couldn't get the fault to repeat. A month or so on same fault, now the Sister in Law doesn't trust the car, so back to the garage. In the meantime they locate a Fabia 1.2 HTP estate at the local Skoda dealer. The seat is back at the garage and they discover the possible fault. The ECU is mounted at the back of the engine bay and the rainwater from the screen hasn't been running out of the drain holes because thay are blocked, so it's been running over the lip and onto the ECU. They opened up the ECU and found it damp with some corroded terminals. They cleaned, dried and soldered some dodgy teminals and the car ran OK for the next 2 weeks before they PX'ed it for the Fabia.

Thanks very much moley. I'll check that out and see if there's any evidence of the same problem. Do you know if I can unplug the ECU to check without causing complications?

[Skoda-on-veg]

There's a guy down here in Sth Wales called Chris Hughes who repairs ECU's. He does a lot of work for the trade, & does a postal service too. His number is 07722288844, & if he can't repair it I doubt anyone can. He generally charges about £150.

Thanks for the tip. I hope I don't need it but, if the worst comes to the worst, I'll give him a call.

Edited 13 March, 2011 by Skoda-on-veg

[powellydicanio]

Hey everyone, It's enlightening reading some of these posts in here as we have a major problem with our Roomster and are getting no-where with our garage. It's an official Skoda garage and all they want to do is strip out and replace the wiring loom!!! At an obvious high price.

We've had all the same symptoms as described and had our throttle body changed last year as a result - at a local garage. The problem are all back and Skoda aren't able to diagnose the problem properly.

Very frustrating so I'd appreciate to hear if anyone has had their problems properly fixed???

Thanks.

[steven carson]

I had one in my work an Octavia tdi when I scoped the pedal I was gettin a good scope pattern so I knew the pedal was ok the fault turned out to be the ecu is ment to supply the pedal sensor with two 5 volt supplys , when I checked it the pedal was only getting 2volts down to one of the supply's so I checked the supply coming out of the ecu at relevent terminals and again 2volts coming out .turns out the drain holes where the ecu sits had blocked causing chamber to flood damaging ecu , I then gave the pedal it's own 5volt supply from another component at the back of ecu plug haven't seen the car back yet and that was bout 3 months ago but officially it needs a new ecu

[powellydicanio]

Interesting stuff thanks. We're taking it to another garage tomorrow so will go forearmed with new knowledge. Cheers.

[Skoda-on-veg]

Hi powellydicanio,

Meant to post an update to my original post some time ago. Also posted a the same question on another forum and must have only updated it there.

Our problem seems to have worked itself out (touch wood). I called Chris Hughes (the fellow mentioned in the post above) who was extremely helpful told me that all the Skodas they've had in with this problem have been down to loose or faulty earth connections - nothing to do with the ecu at all. He suggested getting an electrical mechanic to check it over which was very decent of him considering I was all set to post our ecu off to him to have it looked at.

We had the vehicle checked over by our Skoda dealership who checked all the wiring, said they found nothing at all, and wanted to sell us a new ecu. Funny thing is that, since they checked the wiring, we haven't had a problem. My guess is that they tightened or adjusted the earth connection while checking the wiring and this cured the issue.

Hope you manage to trace the root of your fault. I sympathise - it knocks your faith it the car and you're always waiting for the next failure. Good luck.

J

[pauldazzle]

Glad you got it sorted. Chris Hughes is top bloke, & really knows his stuff.

[jackhughes18]

ive had similar problems.. car starts and ticks over but no throttle response. Numerous fault codes such as throttle body, EGR valve etc but have been advised the ECU is at fault and that they would try to reprogramme it and if this failed I would need a new one.. does this seem a likely cause of my problems?

[nothills]

Does anyone know the Part number of the ECU's that seem to be having a problem, I maybe able to help members with secondhand replacements from stock.

Also the Throttle potentiometer that sits next to the clutch peddle.

[BigW]

Does anyone know the Part number of the ECU's that seem to be having a problem, I maybe able to help members with secondhand replacements from stock.

Also the Throttle potentiometer that sits next to the clutch peddle.

If you would like to do that you would have to become a Sponsor, in the meantime I have edited out the advertising link in your signature. Thanks

[nothills]

If you would like to do that you would have to become a Sponsor, in the meantime I have edited out the advertising link in your signature. Thanks

ooops sorry

[BigW]

ooops sorry

No probs, just a heads up

[rwbaldwin]

There is a connection box under the wiper motor in the plenum chamber. There is BLUE 10-pin connector that for some reason goes intermittant. This carries the signals for the Accelerator pedal position sender. I suspect that water in the plenum chamber 'wicks' along the Tesa tape to this connector.

[Skoda-on-veg]

There is a connection box under the wiper motor in the plenum chamber. There is BLUE 10-pin connector that for some reason goes intermittant. This carries the signals for the Accelerator pedal position sender. I suspect that water in the plenum chamber 'wicks' along the Tesa tape to this connector.

After having said that my problem was fixed the old problem with acceleration loss re-appeared the other night - on a snowy dark night on the A9 of course, and just a few days after having posted saying the problem was fixed. Typical! Thought I'd follow up your tip about the connector and so had a ferret around in the plenum chamber today but couldn't see the blue connector you described. You don't mean the connector that plugs into the ECU do you? Could be I'm just being thick and missing it.

J

[rwbaldwin]

After having said that my problem was fixed the old problem with acceleration loss re-appeared the other night - on a snowy dark night on the A9 of course, and just a few days after having posted saying the problem was fixed. Typical! Thought I'd follow up your tip about the connector and so had a ferret around in the plenum chamber today but couldn't see the blue connector you described. You don't mean the connector that plugs into the ECU do you? Could be I'm just being thick and missing it.

J

If you look under the wiper mechanisn, you will see a thick bunch of cables entering a plastic box about 10cm square that leads to the inside of the car. If you take off the lid you will find a number of coloured connectors.

[Skoda-on-veg]

Yup, thought so - just me being thick. Many thanks for the extra advice rwbaldwin. I'll have another look next weekend.

If you look under the wiper mechanisn, you will see a thick bunch of cables entering a plastic box about 10cm square that leads to the inside of the car. If you take off the lid you will find a number of coloured connectors.

[Skoda-on-veg]

If you look under the wiper mechanisn, you will see a thick bunch of cables entering a plastic box about 10cm square that leads to the inside of the car. If you take off the lid you will find a number of coloured connectors.

Went back into the plenum chamber after reading your reply and think I've spotted the problem. A cable had been put through the front of the box to get it through into the dashboard and hadn't been properly sealed. Looks like water from the windscreen was draining straight down the cable and onto the blue connector you described. Have now throughly sealed the gap round the cable and haven't had any problems since. Thanks once again for the excellent tip. You've saved me a load of grief - and cash.