Accelerator Position Sensor Signal too High

kineticz · Mar 9, 2010

Coming back from a friend's house this evening I come to traffic lights, go to pull away and nothing, pressing the throttle and no response :help:

So got it trailered home and got the code scanner out,

18039- Accelerator Position Sensor (G79): Signal too High
P1631-35-00

18042- Accelerator Position Sensor 2 (G185): Signal too High
P1634-35-00

The EPC light is also stayed on.

According to this, http://forums.vwvortex.com/zerothread?id=3081081 and this http://www.seatcupra.net/forums/showthread.php?t=177103&highlight=18039&page=2

FRIED ECU??

Is the ECU easy to replace? Can the map be transfered somehow from my existing ECU to replacement?

OR could it possibly be that one of the acceleration sensors has caused my recent boost problems and finally failed? Is that likely? Seemed to be the case here: http://www.passatworld.com/forums/archive/index.php/t-227645.html

Epic help required

LEE69 · Mar 9, 2010

That vorterx site also said it could be shorted out 02 wires aswell.

kineticz · Mar 9, 2010

If I'm reading it correctly the guy found his O2 wires shorted and needed to replace the ECU?

Does anyone know where the throttle sensor is located

Thanks

LEE69 · Mar 9, 2010

He said he replaced the ECU then it went again so a short, you never know, if they are shorted out, and you rectify it, it might work.

kineticz · Mar 9, 2010

True that Lee. I'm gonna check the 02 wires, and also the throttle position sensor, do you know where the sensor is located please?

LEE69 · Mar 9, 2010

Throttle sensor is on the throttle body, under the black cover.

cordobabrendy · Mar 9, 2010

Tell me if im wrong here, but your accelerator pedal sounds faulty, disconnect it and give it a good clean.

DannyC87 · Mar 9, 2010

LEE69 said:
Throttle sensor is on the throttle body, under the black cover.

Could be similar to I had Dan; water in the throttle sensor. Electrical contact cleaner cures this. Pop the black cover off the throttle body, be aware there are gears mounted in this so don't do it where you can lose bits; check for water and spray ECC on contacts, let it dry and reassemble.

DPJ · Mar 9, 2010

cordobabrendy said:
Tell me if im wrong here, but your accelerator pedal sounds faulty, disconnect it and give it a good clean.

That's where I'd start...........

kineticz · Mar 9, 2010

DPJ said:
That's where I'd start...........

Disconnect the actual pedal and give it a clean? Or is there a sensor attached to the pedal?

Some sort of guidance would be great.

DannyC87 said:
Could be similar to I had Dan; water in the throttle sensor. Electrical contact cleaner cures this. Pop the black cover off the throttle body, be aware there are gears mounted in this so don't do it where you can lose bits; check for water and spray ECC on contacts, let it dry and reassemble.

Really hope that's the case, I'll give it a whirl.

DPJ · Mar 9, 2010

The sensor on the pedal sends the DBW signal to the ecu.

cordobabrendy · Mar 9, 2010

Being drive by wire, the accelerator pedal is just a potentiometer which sends an electronic signal to the throttle/plenum. Basically I think it looks like the pedal cannot tell where it is positioned (imagine playing a piano, its easier with your eyes open. now close your eyes and let someone move it about, its getting a signal that it wasnt expecting)
Take the pedal connector off and give it a clean, disconnect the battery for ten mins (leave a door open to discharge the residuals left in the system), reconnect the pedal and then reconnect the battery. See how that goes.

kineticz · Mar 9, 2010

Disconnecting the battery also resets the throttle body right?

What makes you think the sensor needs just a clean as opposed to a full replacement? I suppose alot of dirt can get in there off shoes.

Thanks for title change DPJ I was abit miffed last night

cordobabrendy · Mar 9, 2010

I suppose it gets used a fair amount. You could try swapping it with another owner at a meet or whatever and see if it follows the pedal unit.

kineticz · Mar 10, 2010

Tried cleaning them both, no luck, RAC man says it's most likely the pedal sensor so going to replace that.

He says if the ECU had blown the car wouldn't even start? Does make sense but is this true?

kineticz · Mar 11, 2010

New pedal ordered... £76... fingers crossed.

kineticz · Mar 15, 2010

Just finished fitting it, no change, no throttle.

Apart from the throttle body sensor is there anything else it could be? I'm thinking the worst - ECU

But would the car start at all if the ECU was faulty?

LEE69 · Mar 15, 2010

that's an arse

The car starts and ticks over ok, just no throttle?

kineticz · Mar 15, 2010

Indeed Lee, ticks over nicely, EPC light stays on even with the new pedal, codes won't clear. Checked underneath and there are 02 sensor wires hanging down, guess they got cut over a speed bump. A few other 1.8t owners have had this problem and it came down to the ECU itself.

Is a new ECU just a case of a straight swap from another 1.8t? Really need to know this as I can get a refund for my pedal and second hand ECUs are actually quite cheap.

DannyC87 · Mar 15, 2010

kineticz said:
Indeed Lee, ticks over nicely, EPC light stays on even with the new pedal, codes won't clear. Checked underneath and there are 02 sensor wires hanging down, guess they got cut over a speed bump. A few other 1.8t owners have had this problem and it came down to the ECU itself.

Is a new ECU just a case of a straight swap from another 1.8t? Really need to know this as I can get a refund for my pedal and second hand ECUs are actually quite cheap.

If it was the throttle body sensor it would not idle properly. When mine was damaged it was really rough on idle due to the water in the throttle body sensor.

Accelerator Position Sensor Signal too High

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