Brakepad warning light not going away even after new sensors

Hi all My 996 Turbo has an issue with a red "Service wear on Brake pad "warning message that has come up on the dash every 2nd or 3rd time starting or during driving the car. It started the day I got my car back from a porsche specialist who changed the front bump stops and skimmed the rear discs which were corroding slightly on the insides. He has changed all 4 sensors for new ones' but the message is still coming on the same way. The pads themselves are fine with plenty of meat left on them. The cables going into the car seem to be in good shaped and fixed well into position. Any ideas please for what could be the issue and the solution if you have seen this previously ? Thanks Steve

I would start by tracing the wire back from the sensor for a break. It is a simple system...continuity, no light.

Take it back to your "Porsche specialist" and have him diagnose the problem and fix it. You paid him so have him fix it.

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He shrugged his shoulders saying there must a break somewhere in the wiring upto the 'control box's but would need to speak with someone with the Porsche diagnostics machine, he doesn't have one for some reason...( don't ask, I would have thought he'd have one too) Do you guys think changing the front bump stops could have caused damage to the cabling that disappear into the body when viewed from the wheel well ? if not then I'm worried he might tell me they didn't cause the problem...

It's possible. As JTT said, it's a simple system. One of the wires is broken or bad at a connection point - either at the brake pad, or where it attaches to the wheel hub. I had an intermittent issue with brake wear lights that I finally traced it to a broken wire where it connects to the hub. That part takes a little maneuvering to see.

First place to look is the new sensors. Did he replace all 8? Disconnect them at the plug and check for continuity. That will eliminate a simple damaged sensor. If that doesn’t work, you can start hunting for a pinched wire upstream of the plug.

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If it's intermittent and just started after your crack mechanic had it, I would check the connections of the new sensors first too. There's a rubber weather seal that can take a little extra effort to make it seat all the way ( i usually spit on it ).

Ok, thanks for the suggestions. I will pass these on when I speak with him next in case it helps. He replaced all sensors, (each sensor has inner and outer clip) the rear pads had the sensor snip and solder the wires together cheat originally, as apparently the pads are aftermarket versions.

The specialist thinks they have damaged wiring when they removed the suspension struts at the front when replacing the bump stops. His solution is to remove the error light from the dash as anything else will be difficult to trace. Is this the right thing to do ? Seems like a very drastic action, by taking the warning light from the binnacle and so permanantly disabling the sensors ? Should I accept this? He has admitted that they probably caused the warning light to come on in the 1st place disturbing the loom when changing the bumps stops.

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I think you already know the answer to this.

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The first thing I would is to stop referring to him as a specialist and the second would be to find someone that knows what they are doing. ​​​​​​​

Look, I'm a DIY garage guy and I have changed out the pads/sensors multiple times on my cars. This is a stupid simple job and should not be so problematic that you remove the light bulb from the gauge cluster "to eliminate the problem". If they won't check out what they did, have someone else do it. You can also do some simple checking yourself with a multimeter. There is no mystery here and this is not rocket science. Just something is off somewhere and it will probably be a simple fix.

His view is all the sensors are fine. The problem is with the wiring loom. Tracing the break is going to be difficult. The easy answer is what he suggested. He said he spoke with someone who told him this was the best solution as no one relied on the sensors to detect pad wear. I wasn't too comfortable with his solution. So, just in case I was being too sensitive, I thought I would get fellow owners views on here.. I think i am hearing that you guys are saying that he should take the long way around and find and correct the break, despite the time he may need to invest in it. I do feel a bit for him, as these cars are old and wiring could break anywhere if touched accidentally or without knowledge while doing a repair.

Okay, you took your car to a "specialist" and had the brake pads changed and sensors. You did not have a brake pad wear light on before this work was done. Now, after replacement of the pads/sensors the brake wear light comes on. Are you a member of PCA and a local chapter? I am thinking that a knowledgeable local chapter member might be able to help troubleshoot your problem. And, if your rear sensors were soldered together, but are now not, that is the place I would start. Do not feel anything for your specialist, if it is his opinion that the wiring is broken somewhere, then get the car to someone who knows what they are doing.

I'm in the UK. If I go elsewhere, perhaps I'm gonna get hit with many many hours of diagnostic $�$ I'm stuck with this guy fixing it or the warning message I fear. This garage had a pretty good rep tbh, I'm surprised at the black hole of knowledge from them on this tbh

I just think the shop doesnt want to do the work to fix what they broke. The process of testing the harness us not that hard, all you have to do is jumper a few wires and test for continuity. Once they find the corner with the issue they can work there way into the harness.

Ok, so if all 4 sensors are replaced for new OEM ones at the same time (as he has tried), but the warning light still comes on regularly, it is still easy to check "the rest of the cars wiring harness" to see what is causing the light to come on/off. RIght ? Thanks for your comments guys 👍

I've had my struts off several times. I don't see how they could have damaged or disturbed the wiring harness beyond the immediate area of the sensor in the wheel well, therefore significantly limiting the diagnostic work (only within the wheel well). Seems to me to be a LOT more work to tear apart the dash to remove the light. That said, I sort of understand his/her position, as very few paid techs want to do diagnostic work...it doesn't pay (most are paid on flat rate for jobs), and he/she is going backwards fast on this job. If you are able to jack the car up and remove the wheels (even one at at time), I would have a close visual inspection of the wires first. Damage from removing a strut may be visible by a nick in wire wrap or such. Then, find a buddy that has a multimeter, to verify continuity of each of the new sensors (are they a loop). Also check those plugs where the sensors plug in, as mentioned previously. These are easy, DIY steps that will eliminate 80% of the likely issues. If my some bizarre chance they actually damaged the wiring loom, beyond what you can see, that is a bigger issue to take up with them later.

Ok thanks. I have a feeling this conversation this garage is going to be interesting.. lol Thanks again