ABS light still on after replacing sensor

Tiny
LYNDA NEWMAN
  • MEMBER
  • 2004 PEUGEOT 407
  • 2.3L
  • MANUAL
  • 110,000 MILES
I have had my sensor changed on my car left front passenger side. Will the ABS light still come on after I read you have to have the faults taken out of the memory by a diagnostics machine?
Monday, July 16th, 2018 AT 1:03 AM

17 Replies

Tiny
STEVE W.
  • MECHANIC
  • 13,577 POSTS
If the sensor was the problem it will clear itself as soon as you start moving and the system runs its testing cycles. That is because the ABS runs testing continuously to detect any faults. If the sensor was not the faulty item the light will stay on.
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Monday, July 16th, 2018 AT 1:58 AM
Tiny
LYNDA NEWMAN
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When the put the diagnosis machine on it showed it was the sensor. Which has now been changed but warning light still on. I am told the memory still holds the fault and you have to have them taken off getting that done today. Then if they come back on again it is a different fault even though it showed it to be that anyway.
Thanks for your reply.
Kind regards, Lynn
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Monday, July 16th, 2018 AT 2:09 AM
Tiny
STEVE W.
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Not that way normally for ABS. That system constantly scans through itself and if there is a fault the light comes on. Repair the fault and it should go out when the vehicle scans itself again (which with ABS is a constant thing). If it comes back on for the same thing with the same code it was never repaired correctly in the first place.
The normal reasons to get a speed sensor code is a break in the wiring to the sensor due to age and the motion the wiring goes through as the vehicle moves or the connectors get corroded and the sensor signal cannot get to the ABS control module.
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Monday, July 16th, 2018 AT 3:05 PM
Tiny
LYNDA NEWMAN
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Hi and thank you for your reply. It seems to be that the garage that put it on did not do it properly. I had everything turned off and they came back on again. I have had to leave the car with another garage so will know today. The garage that changed it though said it must be a crack in my brakes so another fault another  40 for a diagnostic. I did ask them if they had checked anything before they changed the sensor and they said no! The new garage said they should have, a cog or something. Anyway would a cracked shoe show on ABS? I was told no. I am slightly upset to be honest, the garage that changed it had three diagnostic machines and not one picked it up. I had to find another garage to find it and take it back to the first to have it changed and seems they did not repair it correctly. So it is now back with the one that diagnosed it properly the first time. Maybe as I am a women they think we know nothing but one thing I do know is when I called them back they were sarcastic and not nice. As I called them out they admitted only to change the sensor and nothing else.
So now I have to have the repair repaired by a different place and I am very upset. I would like to thank you for all your help and will let you know what happens.
Kind regards, Lynne
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Monday, July 16th, 2018 AT 11:46 PM
Tiny
LYNDA NEWMAN
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  • 12 POSTS
I hope you can understand all that babble, but as a women sometimes they think you know nothing. All I have changed clutches and brakes on my old cars and when you have a car you normally this sounds mad but know when something is wrong with it bring back the old cars that told you nothing was wrong you had to find it out yourself. I miss those days this new tech really does my head in funny though. I was driving to blackpool and doing 70 mph when a warning light came on showing all the tires red I got off the motorway and went to a garage the mechanic said do not worry they just put them there to scare you.I found a petrol station opened the bonnet and the steering fluid was coming out the top. I managed to get some out lights went off. Even the people that changed the sensor who could not find the fault said it is because the weather is so hot! Hope that made you laugh it did me and my family. Well I will be leaving a review on the site and it is not going to be good. Once again thank you so much for helping me. I will be biting what nails I have left to find out how much the repaired repair will be today. With kind regards, Lynne
Thanks Steve
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Tuesday, July 17th, 2018 AT 12:07 AM
Tiny
LYNDA NEWMAN
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Okay another update: Not the sensor been double checked and they are working fine, but still ABS light on all the time. Might be a faulty wiring. So now have to have it checked by a Peugeot man that just deals with these cars.
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Tuesday, July 17th, 2018 AT 6:11 AM
Tiny
STEVE W.
  • MECHANIC
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A cracked brake shoe/pad would show up as noise and possible a shake when applying the brakes. It would not usually trigger an ABS light. However a cracked ABS tone ring, bad sensor, broken wiring, bad wheel bearing or faulty ABS module can all cause an ABS light. All of which are basic checks a tech should look at if there is a light depending on the code in the system. That is because many of them can mimic each other. For instance a cracked tone ring will show as an intermittent signal, as would a failing wire or loose sensor.

The problem many time is that shops do not keep up with the technology on vehicles. These days there are more computers on board the average car than were on the space shuttle! However, once you learn how they operate and understand that the codes that come up are not "this part has failed, change it" but rather "I see a fault in this system, please check over the associated parts" it gets far easier to do a proper repair. But there are places that refuse to learn the systems or just opt to do what many here call "fire the parts cannon" IE: let's swap any part related to the system in the hope that one fixes it. That gets very expensive and may not actually repair the problem. That is when you get an explanation of "Well we got code P0XXX before and if it comes back it must be something else"

This is one of the things that makes the industry look like crooks. That and the "they do not know what is going on so charge them more" attitude in some shops, being the larger ones. Thing is that doing the proper diagnostics and then replacing the actual faulty part is 99% of the time faster and easier overall. Which also means the vehicle gets repaired and the customer gets a lower bill.
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Tuesday, July 17th, 2018 AT 10:09 AM
Tiny
LYNDA NEWMAN
  • MEMBER
  • 12 POSTS
  • 2004 PEUGEOT 407
  • 2.3L
  • MANUAL
  • 110 MILES
Okay, ABS light came on showed passenger side sensor left. I had it changed still on. I took it to another garage who put the car up and tested them all and they all work, but ABS light still coming on. This is driving me round the twist. Could it be wiring?

Please I cannot cope anymore.
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Tuesday, July 17th, 2018 AT 2:11 PM (Merged)
Tiny
LYNDA NEWMAN
  • MEMBER
  • 12 POSTS
Now looking at the brake light switch under brake pedal which will be done tomorrow. This car is taking over my life.
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Tuesday, July 17th, 2018 AT 2:13 PM
Tiny
STEVE W.
  • MECHANIC
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Brake light switch should not cause a wheel speed sensor problem. I would be willing to bet the issue is either the wiring between the sensor and the module or a connector. If they unplugged the sensor and tested at the sensor side connector that leaves the remainder untested.
The fastest way to see if the sensor is reporting would be to put a scan tool on the car select the live speed data from the sensors and drive it around the block. If you are seeing say 25 kph at each sensor then there is an issue with the module. If as I suspect you see 25 kph at three wheels but the left front shows 0 then there is a wiring issue.

Some days I wonder if I should just own a bicycle, then I remember that the closest store is twenty miles away.
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Tuesday, July 17th, 2018 AT 4:37 PM
Tiny
LYNDA NEWMAN
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I took it to a different garage to have all the sensors checked yesterday and they were reading perfect on the diagnosis machine. But I will say one thing when you turn it over and drive straight off it judders when you put your foot on the brake then ABS, ESP light come on and it stops. But the lights ABS, ESP are still on. And so is the brake light bulb.
Thank you Steve there is only so much patience a person has. Yes a bike would be so much better.
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Tuesday, July 17th, 2018 AT 10:37 PM
Tiny
STEVE W.
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That judder would be because the ABS module is activating as you use the brakes. It means that regardless of the sensors reading perfect, the ABS module is not seeing the one that is setting the code. As soon as the code sets it turns the ABS system off and turns on the lights to tell you there is a problem.
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Tuesday, July 17th, 2018 AT 11:45 PM
Tiny
LYNDA NEWMAN
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Cheers Steve, so having had them tested by four different machines what do I do next? I really am at my wits end.
Thank you Steve. I am nearly in tears here and my patience is wearing very thin. I do appreciate what you have done and I do not know where else to turn.
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Tuesday, July 17th, 2018 AT 11:50 PM
Tiny
STEVE W.
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Not sure what to say. I just know what I would be looking at as the problem and how I would do it. I would start by connecting a scan tool and go for a short drive while watching the speeds the sensors are sending to the system. Then if one was reporting wrong I would connect an oscilloscope to the wiring at the ABS module and see exactly what is going on.
One of the drawbacks of this type of assistance, I cannot see what they are testing or seeing. Someday there will be auto repair by remote, like they have for surgery.
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Wednesday, July 18th, 2018 AT 6:49 PM
Tiny
LYNDA NEWMAN
  • MEMBER
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I wish Steve some electric person is going to look at it today for faulty wiring. I have got to I do not care anymore now and someone has done what you said about driving it. I had a leak on steering fluid and that has stopped leaking how about steering pump? God, I am clutching at straws but it is mad how the leak has stopped.
Thanks Steve wish you were here, I could have brought it to you.
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Wednesday, July 18th, 2018 AT 11:38 PM
Tiny
LYNDA NEWMAN
  • MEMBER
  • 12 POSTS
Hi and just an update which your probably just as sick of it as me. The near side front bearing had gone. I got my car back yesterday thank goodness no ABS ESP lights or back brake lights or knocks all done now. No car finance for me I was looking that way.
Thanks for your help Steve.
Kind regards,
Lynne
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Thursday, July 19th, 2018 AT 8:12 PM
Tiny
STEVE W.
  • MECHANIC
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That would throw the tone ring out of alignment. Sort of surprised they did not see it while doing the other work. Or noticed the issue when they tested the sensors as it would have been erratic. But at least it is repaired.

Thank you for using 2CarPros. Com. Return anytime with your automotive questions.
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Thursday, July 19th, 2018 AT 8:35 PM

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