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D2 - Engine Bay Everything under the bonnet

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Old 11th April 2019, 10:16 PM
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steamship steamship is offline
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Location: Londonderry, Northern Ireland
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Default ABS and Traction Control Lights... AGAIN!

Well, as the title hints at, I'm having issues with these two pesky lights, and today just pushed me a bit too far.

The car was SORNED from the end of April last year until January, and started throwing up these two lights (at times). The only relevant code I get when doing a scan is this one:

16486 - Mass Air Flow Sensor (G70)
P0102 - 35-00 - Signal too Low

I also get the odd gearbox code once in a while, and that's because of the F125 switch, which I've yet to replace.

Having scoured the forum for answers before, and again now, the common suggestion is to replace the MAF. So that is what I did yesterday, with a 'proper' BOSCH one (I must have been feeling flush at the time). All the electrical contacts were pristine as well. Just from reversing round the side of the house, you could feel the difference, and I had to have my foot on the brake as I drove (it drove) down the lane. BTW No lights on the dash. Went to my appointment, which was mainly town driving and stop/start, and then a slight detour on the way home. This is when I noticed something odd. Car refused to go beyond 2,500rpm, sort of like an engine limp mode. Got home and parked up, scanned it, and nothing new.

This afternoon, I had to go for another appointment, and this time the car started and then died. Tried this about three times, with the same result. Then tried it a couple more times using various amounts of throttle, and it still died. I was now running late so put the old 'unbranded' MAF back in, and away it went.

All the vacuum lines were replaced a few years ago, so doubt any of these have perished in that time, and I also checked the brake switch to ensure that it was still working properly (VCDS Engine block 066).

Now, it's the symptoms of how these lights appear... and disappear that has me puzzled. Most of the driving I do now is short runs of less than four miles, and mainly town driving, although the car could sit for four or five days unused. It's only on the odd longer journey of around eight miles that I see the variances. The symptoms, which I can pretty much replicate, are as follows:

1. Cold start, no lights on dash, and short drive to destination
2. Car sits for about an hour
3. Warm start, both lights now appear
4. Longer drive out of town and lights disappear

I can understand a fault causing the lights to appear, but can't fathom why/how they disappear. My next course of action is to check the BOSCH MAF settings with VCDS, which I've done before, to see if the MAF is faulty, and get a replacement. I can also run the same tests on my current unbranded one, to see if it has gone out of tolerance.

Sorry it's a bit long, but wanted to cover everything I've checked and done, as well as how the lights are behaving.
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2001 A8 D2 FL 3.7 Q - LPG Conversion, Engine: AKC, Gearbox:FBB, Colour:LY5X Aqua Blue pearl effect, Interior:WJ light beige/dark beige valcona leather with burr walnut inserts

My DIY jobs - Replaced alarm horn, Replaced Coolant Temp sensor, Updated RNS-D firmware, Installed Reversing Camera and Digital TV, Dashcam Installation, Retrofitted Rear Blinds, Auto-Dimming Rear View Mirror, Chrome Boot Struts

Sold! 2008 S8 D3 5.2 V10 - Engine: BSM, Gearbox:KLW, Colour:LY7F Suzuka Grey Pearl Effect, Interior:Black/Black with Silver/Black valcona leather with carbon atlas inserts, Bang & Olufsen, Heated windscreen, Soft-close doors, TV, DAB, AMI, Quad Zone, Auto Boot, Auto dim Mirrors, Keyless entry, PDC with rearview camera, AFS II Headlights

My DIY jobs - Fan Jet Windscreen Washers, Retrofitted Electric Side Blinds
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