ABS wheel sensor?

[Defenderben]

Hi All

 

Our little Citigo has started throwing up an ABS wheel sensor communication fault (left front wheel) .

 

I have Googled the image of the unit which appears to be a single bolt fixing with a plug on it, how simple is it to replace?

 

I have a fairly comprehensive range of tools but cannot see any schematics online of the layout or where it actually is.

 

Any help/pointers/ images appreciated.

 

Regards

 

Ben

[Hyphons]

@Updown789 is usually a pretty knowhow guy, what do you think? Faulty sensor or it just needs a clean?

 

[Updown789]

Take the wheel off and check the plug from the abs wire hasn't come undone. It is behind the disc and it is attached to the shock absorber. If it looks OK then next step would be to replace sensor. As you say I think it is just one bolt and pull it out.

[ronime]

Wheels speed sensor failure is a common failure on MINIs. Theoretically easy to replace but in practice often rusted solid where the sensor locates in the rear face of the hub on older cars.

Edited 23 December, 2017 by ronime

[Snaefell]

17 hours ago, Hyphons said:

@Updown789 is usually a pretty knowhow guy, what do you think? Faulty sensor or it just needs a clean?

 

 

> Faulty sensor or it just needs a clean?

 

Well spotted.  A high % of wheel sensor (WS) problems are related to a dirty contact with the 'phonic' wheel (PW) on the disc. 

You can try pressure washing the hub area. 

If that fails, remove the road wheel and WS and clean the sensor face by wiping with a clean rag.

Check the resistance (Ohms) of the sensor with a multimeter and compare the figures  with a known functional sensor.

Then lubricate (any grease will do) the outside of the sensor where it contacts the hub.  This makes it easier to remove next time around.

GENTLY tap the sensor against the phonic wheel and pull it back a fraction (approx. 0.012" or 0.3mm) OR just sufficient so that the sensor and PW don't make physical contact. 

Spin the brake disc to check clearance. 

You may need to connect up to the 16 pin diagnostics plug to delete the malfunction indicator lamp (MIL) or yellow engine light.

Some systems need the vehicle to exceed a certain speed (approx. 15km/h) before the wheel speed sensor resets itself.

Good luck.

 

Snaefell, Marown...IoM

[Defenderben]

Thanks for all the replies.

 

The car is a 2012 - 62 plate always garaged and only covered 12,400 miles, so was surprised it chucked up this fault. Suspect may be build up of dirt etc.

 

It isn't on all the time, you can get a whole journey of 15 miles without it then next time "bing" and it's on. The garage did the code reading and confirmed it was front left wheel sensor.

 

Thanks again.

 

Ben

Edited 25 December, 2017 by Defenderben

[Defenderben]

Oh well, finally decided to get the car looked at after the fault light decided to stay on constantly.

 

Not good news, the garage have replaced all 4 sensors and checked the wiring back to the ABS pump/ECU unit.

 

Took the new sensors off again as did not sort the fault; now it is the ABS pump/ecu :(

 

A new pump is over a £1000 alone or remove the existing and send to a specialist for repair @approx £250 plus all the other labour it will end up around £500 -£700

 

:((

 

Can't believe it on  a car with around 12,500 miles.

[Defenderben]

Update

 

All fixed

 

Touch and go as a brand new ABS pump/ECU fitted and coded was £1,850.00

Took a chance on buying a second hand ABS unit from a 2012 VW Up with 38k miles when scrapped, for £65 incl delivery.

 

Another £200 for fitting, coding and full brake fluid replacement.

 

So car back and All clear of faults for £265.00 if it hadn't worked it was off for a trade in, as the trade value of the car was only just over £3k.

 

So what started as a simple error code saying the front left ABS sensor was faulty ended up as a complete new unit on a 6 year old car with just over 1years average mileage!

 

So glad I didn't tackle changing the sensor

[Emil]

First brake fluid change after 3 years and then every 2 years. Do you know if brake fluid was charged as should? 

 

One good reason to change brake fluid as recommended. 

[Defenderben]

It was done on its 3rd year service @ Skoda dealer. No other brake fluid changes until now.

[Emil]

Well if and when it was electrical issue brake fluid change interval doesn't matter. But as ABS pump isn't cheap it's good to replace fluid every now and then. I'm saying this because some people thinks it's not needed. Moisture in the pump can't be good. 

[Rooted]

Some people think the moisture content should be checked in brake fluid with a tester and do that and change the brake fluid if needed, maybe not every 2 years after the first change though just because that is the Manufacturers recommendation or guidelines or even schedule.

Odd how many Fleet Cars are not serviced to the schedules. 

Only a few years back it was first at 2 years then each 2 years for Brake Fluid changes.