16955 and stubborn check engine light

Pinkythelabrat

Pinkythelabrat

A2OC Donor
My brake lights were only coming on intermittently I noticed and I was off to an MOT when I threw a 16955 - brake switch.

I pulled the panels, removed the switch and used contact cleaner and a few vigorous pushes and put it back. Seemed good. All lights worked with each pedal push and the garage couldn’t find any fault on the switch.

Except... I can’t clear the flashing glow plug!

OBD2 scabs show NO faults with the car. None! I clear faults anyway and the EML temporarily goes off for a minute maybe then ‘flash, flash, flash’.

Is there a better way? Could the switch be operating perfectly, not throwing a code, but still be faulty and upsetting the EML?

Help.


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If the brake switch gave the error before,then for the cost of a new switch it might be worth changing it to rule out the old switch being suspect.i would imagine the glow plug symbol is flashing for a reason,so maybe a full scan is needed?
 
Pinky, I'm watching this with great interest.
I have the same problem, I to was advised that it was probably the break light switch but after buying a new one it still did the same.
So after thinking it might be a dud or just not up to the job not being OEM I decided to swap out a known working one from one of my other A2s.
Same year, same model but the same result, glow plug light flashing.
I'm told that the glow plug light flashing can also indicate that there is something else wrong and not just the break switch.
Best of luck tracking the fault down and I do hope for your sake that it is just the break switch.

Just out of interest, did your car ever go into limp mode at anytime?
This one does.
 
Some cars need to be driven a short distance after replacing the brake switch. You need to drive the car, steer left and right and brake a few times. The ABS , ASR and ESP systems then get reset as the system "learns" the switch.
 
Sorry, I was meant to say that I did drive the car around the eatate and the fault returned each time.
Sorry pinky, I don't want to jump into your thread with my problem and take it over, but if I get anywhere with my problem I will chip in.
 
This is a community forum. I’m happy for everyone to chip in and see what can be learned.

My worry was that it was something else so I’ll pull out VCDS lite later and try a better scan but normally the OBD system has shown any errors. Weird coincidence though for timing.

I’ve ordered a new switch already but it’ll be a few days. I went for a Febi one as that is apparently OEM quality. There seems to have been an American recall of the brake switches very early in the life of the A2 and the switch was replaced with a more reliable version but I couldn’t make sense of the part numbers and don’t have the facility of some members on here with the part number finding. There was talk of purple replacements but these looked different shapes to me.

I have driven the car about 15 miles over three journeys with the switch in and the lights are coming on every push.

It drives beautifully and has never gone into limp mode ever. I hope never to experience it.

New switch by Tuesday apparently but I’ll maybe pull it apart again later and see if I’ve pushed the current one in wrong or something.

Thanks.


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The battery disconnect can sometimes cure faults, but so can a fully charged battery with clean terminals and good earths.
 
Pinky, when you do connect your VCDS lite later, make a note of every thing it says, even take a photo of the screen like I did with mine.
I have had two different fault codes but the same break switch problem.
My first result was the same as you got, 16955, but another rescan using VCDS lite came back with......... 00526, break light switch - F. 008 implausible signal, intermittent.
 
Another thing worth trying which I found after a couple of false readings from an engine scan and "intermittent" faults being stored was to unplug and clean the ECU multiplugs..........after years of use the connections can become tarnished, not enough to see but enough to upset canbus/signals.
Worth a try and not going to cost anything......
 
thanks for all the suggestions. I think that’s it fixed

Symptoms: VCDS showed the fault code and when cleared it immediately reappeared. VCDS reported the EML as not active but the glow plug symbol kept flashing. When I looked at the ABS section it reported the brake pedal correctly - not activated and activated. Brake lights all lit perfectly - no flicker or delay - at all.

I reseated all the bulbs - no change.
Checked the fuses - fine.
Pushed the pedal to check the lights - all perfect... but... I noticed that the lights lit immediately on touching the pedal. There was almost zero pressure needed to light the lights.

I pulled the switch out and changed the plunger depth so there would be a small bit of pedal travel before the switch activated. Still before any pads hit metal but a little pedal travel was needed. That seems to have done it.

I wonder if maybe it was just a tiny bit activated hard up against the pedal and wasn’t quite crossing the ‘on’ threshold but was giving some voltage bleed which was annoying the car EML.

Drove for 10mins with no recurrence. Previously it would show after keys in within 10secs. Even without pressing the pedal.





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highly likely, there is meant to be some free play before the pressing the pedal activates the switch

By the way the American recal from memory was on Golf's, certainly not A2's as they never sold the A2 in the USA
There is one A2 in Texas that I know of as I have sold the guy some parts over the years

PAul
 
Yes some switches do appear to be not quite setup when you buy them. Not a big job to set the plunger but easily missed.
 
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