Bit of a strange one in our AZQ-engined 2005 Fabia on Sunday.  On the way to an important appointment in Northampton, but had left plenty of time in case of traffic on A34/M40/A43.  Cruising north on the A34 at 55ish tucked reasonably close behind a truck; there was a strong following wind from the South.

 

EPC light appeared together with noticeable but not dramatic power loss. Seemed smooth just not as much go for that particular accelerator position. Hindsight says I guess that was Limp mode kicking in?

 

First thought "Oh crap, this had better be something I can fix at the roadside; expensive appointment to miss".

 

Pulled into a handy Parking refuge just a few hundred metres further up and hoicked the handheld scantool out of the glovebox.  Left engine running, and it was not sounding or feeling happy, almost misfire-like but with the benefit of hindsight from shortly afterwards, probably the throttle plate hunting around cyclically.

 

3 DTCs reported as follows

17950

16490

17579

In the heat of the moment I couldn't work out how to clear them as I don't use that scantool often. None of the codes seemed familiar, so was keen to look them up in the little handbook that came with the tool, also in the glovebox.

One after another they were all absent from the book!

 

"Get googling please hon, while I have a look around under the bonnet" said I, as I switched off ignition and released the bonnet.

 

Nothing leapt out at me as amiss at a glance, and soon I was getting info about the 1st of the codes 

 

17950 Angle Sensor 1 for Throttle Actuator (G187): Implausible Signal.

 

Told her I thought that was maybe one of the (2) accelerator pedal position sensors but she soon corrected my bad memory while reading about it and said "no, it's the throttle position not pedal position".  I should've got that from the word actuator.

So while she moved onto the next code I unplugged the TB connector and had a quick look at the wiring locally and the contacts, all of which were fine. Plugged it back in.

 

16490 Manifold / Barometric Pressure Sensor (G71) / (F96): Implausible Signal

 

Had a brief attempt at eyeballing the MAP sensor but soon gave up.

 

17579 Angle Sensor 2 for Throttle Actuator (G188) Implausible Signal was the last google result.

 

Restarted the engine, smooth idle, no EPC light; thought "right, let's just drive, quick as we reasonably can to close in on N'hampton".

Totally uneventful onward journey, no symptoms, no lights, got there in good time.

Same on return journey later on.

 

Scanned with VCDS at home, same three codes still there, which wasn't a surprise as I hadn't cleared them at the roadside. Cleared them with the laptop.

 

Took the car to work next day, no misbehaviour on the way, no codes when scanned on arrival. Logged MVB62 on the way home, which is the pairs of throttle position and pedal position sensors. No glitches at all apparent when processed gently in excel (sum of two throttle sensors should = 100%; one of accelerator position sensors always twice as much as other).

 

Been a couple more days of short but uneventful journeys since, will scan again this evening with VCDS if I remember, but a bit mystified at this point.

 

Only thing I vaguely wonder is that maybe the combination of strong following wind, mild tailgating of truck and low cruising speed may have got the engine ECU looking at manifold pressure versus throttle position numbers that were out of plausibility range??  Seems a bit far-fetched that nothing similar has ever happened to that ECU before.  

 

 

 

 

 

 

 

 

 

It was exactly what you just said, a throttle position too light for the calculated engine load at that road speed.

How weird

Just scanned it again. No faults have returned. 

🙂

Definitely an odd one.

1 hour ago, Breezy_Pete said:

Just scanned it again. No faults have returned. 

🙂

Definitely an odd one.

 

If your car is anything like me, it's just having a moment at having to think too much.

//Read time since last fault
//Value in days

int time = Read_FC_Timer;
if (time < 10) {
  cout << "Set 1 Fault Code in random module";
} else if (time < 20) {
  cout << "Set 3 Fault Codes in random modules";
} else {
  cout << "Turn on all warning lamps, Make SOS Call";
}

I think they have this in the Gateway firmware code

 

 

Yes it's a joke, and I can barely write C++

Edited 27 July, 20223 yr by varooom