Fault Found ABS Sensor N/S/R ....(Problem Ongoing)

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c3owner
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Fault Found ABS Sensor N/S/R ....(Problem Ongoing)

Post by c3owner »

Hello

I am hoping someone maybe to help as the past two weeks my car has slowly become worse.

I have a C3 1.4 cool 57 Plate. Basically, I am use to problems with my C3, had central locking issues, back left and right indictor issues (faulty wiring) and a head gasket issue.

Now for the past two week I have had a fault come on which said "stop braking system error". The ABS and the Brake red ! light would appear for a second and the disappear. After a week it effected the car by suddenly getting a ABS system error and then would get heavy power system (like it had become disabled) and "-.-" where the speedo normally would show. I phoned the RAC and by the time they arrived the car functioned again. Anyhow, I took it to a garage where they changed the brake switch. They said if this didn't work they believed I would need a new ABS pump. They did however clear all my past faults so it would be less confusing when a new one resurfaced.

Anyhow, a few days later the warning lights returned. Of course because of the expense of a new ABS pump I wanted another opinion. So I took it to another garage. At first they couldn't read any faults. So they got their auto electrician out and he re-established comms to the D.L.C. and scanned E.M.S and A.B.S and found no faults past or current. So they gave it back to me and said if the problem arises again bring it back in. So I have. They checked underneath to see if there is a mechanical fault. Doesn't appear to be. So they are getting auto electrician out again on Friday.

However yesterday, worryingly, as I was driving the ABS and brake system lights were becoming more frequent until I then got two new errors, seat belt and air bag. That happened once, and hasn't been repeated and the lights went off but on the journey my speedo then went to "-.-" and power steering become heavy. The speedo corrected itself by end of the journey. The power steering kick back in once I turned the engine on and off. Since then just the usual two faults, intermittent but frequent ABS and brake system error lights.

So I am totally flummoxed what is going on. I have seen a similar thread to a guy in the diesel questions forum and after four month he gave up after it seemed no one could locate the fault. Has anyone has similar issues like this? It would be great If someone could shed some light as to what's going on because just fearful I will pay for repairs without actually fixing the issue.
Last edited by c3owner on 15 Apr 2014, 17:57, edited 1 time in total.
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Re: HELP! Intermittent Warning lights but no fault codes!

Post by RichardW »

Hi there

This sort of thing can be caused by a poor battery, battery or earth connection - multiplexed CItroens do not like the battery voltage being a bit on the low side. Get the auto sparks to test it - for the cost it might be worth just sticking a new one in.
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Re: HELP! Intermittent Warning lights but no fault codes!

Post by Sl4yer »

Hello.

We had this on ours a couple of years ago. Turned out to be the ABS ECU failing.

It started with a regular ABS fault, which could be seen on the Lexia. But it was intermittent, and sometimes appeared on different wheels. This progressed to full (but intermittent) failure, with "--" instead of the speed, power steering 'failure', and failure of automatic wipers and anything else which uses the speed signal. (The vehicle speed is derived from an average of the front wheel speeds, as measured by the ABS system, so a fault there wipes out the speedo). A new battery didn't fix it, although it's always a good starting point with these things as RichardW says (a new battery just sorted a lot of the gremlins with the pneumatic suspension on my father's C4GP).

I think the new ECU and valve block was about £800 plus fitting. I believe the ECU is coded to the vehicle on installation, so a second hand one can't be used.

Sorry it isn't better news.

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Re: HELP! Intermittent Warning lights but no fault codes!

Post by c3owner »

Thanks for the replies.

See what happens tomorrow. I will ask him to check battery and earth connections. I am just slightly concerned about how difficult it is the locate where the fault is coming from. They have had the computer not respond when they check the ABS diagnostics yet other times it was responding but wouldn't complete the ABS diagnostic.

Ive already paid out for a brake switch and labour and the thought of £800 isn't great, but the fact of wondering if it will cure the problem or not is even more concerning. Ive searched other forums and people with similar problems end up paying out but the problem doesn't become solved.

I resisted going to the back to the dealership but maybe this might have to be an option.
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Re: HELP! Intermittent Warning lights but no fault codes!

Post by Stickyfinger »

Are they using a Lexia ??..........standard code readers often do not help much as they do not report the faults correctly
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Re: HELP! Intermittent Warning lights but no fault codes!

Post by c3owner »

Well the two fault codes that were shown were ABS pump / connection wires to the BSI unit.

I was told that until the lights come on permanent that it couldn't be determined which fault is the one causing the issues.

This isn't any help to me as when I drove it this afternoon the speedo "-.-" comes on and the power steering goes heavy so I need a solution and not wait until the car finally decides.

Im not taking it to a dealership, who were gonna charge me £87 for diagnosis and even if inclusive still charge me, but a Citroen specialist independent garage who will charge me £35. They wont charge if inclusive.

I am slightly bewildered and bemused. Its one thing to have a fault and you need to fix it and you get annoyed about the expense. Yet this is just strange. I have a fault(s), cant determine what is causing them and having to supposedly wait to it gets even worse before I can do anything. However, I must say the garage I have taken it too 4 times have only charge me once and that was to make the faults register on the computer. Although slightly concerned why the faults wouldn't initially register on their scan equipment. This is one reason I am taking it now to a Citroen specialist so to see is their scanning equipment can perhaps get to the root of the problem as Im hoping their equipment will be more efficient.

The worse bit about today was when a I was speaking to this Citroen specialist/sales person at the garage I brought it from and he tried to tell me (after I rattled off all the problems I had) that basically all cars parts are made by the same people. If that is so, why bother even getting an expensive Citroen :roll: Apprantely, there are "unlucky" cars. When I told him I had a head gasket and done less than 25,000 miles I got no response and just said yeah "I must be really unlucky".

Its like the never ending fault.....
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Re:HELP! Intermittent ABS Warning light / Fault ABS sensor N

Post by c3owner »

This is becoming abit of a nightmare now.

So took the car to a Citroën specialist independent garage. They scanned the car and saw I had a some faults registered but only one came up as permanent. ABS sensor to the passenger side (N/S/R) so they had a look and believed the wires and sensor were fine and concluded that as they was lot of brake dust it must be this.

Cleaned it all up and charged me £80. I thought brilliant. Sorted.

Drove it home fine. Drove it to work fine. And then just as I got home ABS light came back on with brake system error. Speedo went "-.-" and power steering went heavy. Then it flashed up seat belt and airbag fault. So I waited another 5 mins after I got home and took it for another spin. ABS light camed on after a few mins with brake system and ABS system warning. Then after two mins or so the light went out again.

Bit worried because this issue could go on and on it seems. What I don't get if it says permanent fault with sensor how after cleaning it and putting it back together why didn't it come back on when re-scanned?
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Re: Fault Found ABS Sensor N/S/R ....(Problem Ongoing)

Post by Old-Guy »

There is "permanent" as in the sort of time frame that electronics work in (seconds) and permanent in the time frames that humans relate to (hours/days). What you describe is typical of faults in complex electronic systems - until the fault goes really 'hard', everyone is chasing ghosts. Apparent 'fixes' may often coincide with the fault doing a regular dis-appearing trick.
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Re: Fault Found ABS Sensor N/S/R ....(Problem Ongoing)

Post by Sl4yer »

You will only get the speedo failure (and the associated power steering issue) if the front sensors are not reading, or if the ECU cannot deliver a speed signal. A rear sensor cannot cause this - ours managed (on a different occasion) to completely cut a sensor wire at the back and the speedo was unaffected.

Ours showed intermittent rear sensor issues before the ECU problem became permanent. From memory, the left rear sensor returning very high numbers which are impossible. This led me to believe that there was an ECU or CANBUS problem - this was confirmed by my garage who swapped sensors, but got the same readings.

I'm convinced you haven't got a sensor fault, even though the diagnostics will show a mismatch between different sensors. The live data needs examining - an ABS sensor is really quite a simple thing, and will usually either work or not!

Where are you located? Is there anyone near you with a Lexia?

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Re: Fault Found ABS Sensor N/S/R ....(Problem Ongoing)

Post by c3owner »

I'm in South Devon. I using a Citroen specialist garage. So I imagine they have a Lexia. I don't want to take it to the CITROEN dealership because they said they would charge me £80 just for a diagnoses, even if inconclusive (e.g. more than on fault showing). They are pretty expensive and over priced however my hand might be forced eventually.

I am just worried I could be paying for jobs that don't even need to be done but the problem Is the faults the current garage are getting back tells them to look in that particular area. I'm beginning to think If its not a wiring issue, then its the ECU * :roll: gulp*

I have seen someone mention problems like mine and they said if it intermittent its a short on the front section wiring loom. Not sure how to play this if a "permanent fault" cant be located. Is going back in on Thursday so take it from there!!
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Re: Fault Found ABS Sensor N/S/R ....(Problem Ongoing)

Post by Sl4yer »

It's possible that there could be a bad connection to the ECU. But examination of live data on a Lexia will show what's going on.

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Re: Fault Found ABS Sensor N/S/R ....(Problem Ongoing)

Post by Hell Razor5543 »

If you suspect a dodgy connection use a proper contact cleaner and toothbrush to clean up the plugs. Don't use WD49, as this is a water dispersant, and not designed for clean connectors.
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Re: Fault Found ABS Sensor N/S/R ....(Problem Ongoing)

Post by c3owner »

Sl4yer wrote:You will only get the speedo failure (and the associated power steering issue) if the front sensors are not reading, or if the ECU cannot deliver a speed signal. A rear sensor cannot cause this - ours managed (on a different occasion) to completely cut a sensor wire at the back and the speedo was unaffected.

Ours showed intermittent rear sensor issues before the ECU problem became permanent. From memory, the left rear sensor returning very high numbers which are impossible. This led me to believe that there was an ECU or CANBUS problem - this was confirmed by my garage who swapped sensors, but got the same readings.

I'm convinced you haven't got a sensor fault, even though the diagnostics will show a mismatch between different sensors. The live data needs examining - an ABS sensor is really quite a simple thing, and will usually either work or not!

Where are you located? Is there anyone near you with a Lexia?

James
You say you had ECU problem, can I ask what was your issue in the end? What repair did you need on the ECU? I am concerned it will end up being a ECU problem but that whole ECU unit will need to be replaced which is very expensive I hear.

Strange thing at the moment is that since the mad 5 mins on Tuesday morning the car's ABS light hasn't come on since. I mean normally once the ABS light first comes on it will become more of a regular occurrence thereafter but since there has been nothing. Even took the car out for a extended run but still nothing.

With the fault on the N/S/R they said the sensor and the wires were fine so it makes me think they have lexia because they could test the wires. Tomorrow morning it goes in so see what happen next *gulp* !!!
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Re: Fault Found ABS Sensor N/S/R ....(Problem Ongoing)

Post by Sl4yer »

ECU failure as I described above. The garage I used did say they can sometimes be repaired, but I suppose it's hard to decide to make that decision.

It ended up with permanent speedo failure, and ask that goes with that. When it went into the garage, they were unable to connect to the ECU at all. The ECU and valve block were replaced.

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Re: HELP! Intermittent Warning lights but no fault codes!

Post by wheeler »

Sl4yer wrote: I believe the ECU is coded to the vehicle on installation, so a second hand one can't be used.
You can use a second hand ABS ECU no problem, it's not 'coded' to the car as such, just configured to the spec of the car, tyre size,type of gearbox etc. The configuration can easily be changed with Lexia.
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