Shows the location of the ABS/ESP unit near the battery; access may be easier from below - remove left front wheel and mudguard under wing
Shows the location of the yaw sensor (accelerometer) under the handbrake lever
Remove the plastic cover under the handbrake to locate. It is held in place by one (maybe two) bolts.
You can turn ESP off - but it still leaves a light and would be an MOT failure in the UK. In any case it should turn back on automatically after the car reaches speed over 20-25mph (30-40km/h)
As the fault could be in the ABS/ESP unit or the ABS sensors on the wheels (or the wiring in between!), a good diagnostic tool will tell you whether it's a sensor outside the unit or a faulty ESP unit.
William Wadling's local garage diagnostic found a fault with the yaw sensor (accelerometer) under the handbrake (see above). You can purchase off the internet: second hand about £40 reconditioned about £80. Local garage charged £135.00. Now working OK.
Yves de Muyter points out that there is also a sensor that measures the angle of the steering wheel. Using PP2000, Rimas Baltrusaitis did a calibration of the "steering wheel angle sensor" and the "ESP/ASR not functioning" light on his 1007 dashboard went out.
The ABS unit is quite low down - it could have corrosion in the plug/socket over the years so unplug and check. I had a fault like this on my Jaguar, water leaking in over time - the plug/socket was quite a mess when I eventually discovered the fault.
You can replace an ESP unit with a used one from another car - some UK based companies re manufacture these units.
If replacing with used one, make sure the type fits your car, as there are 2 versions of this unit. Variant 1 with external braking pressure sensor and variant 2 with internal pressure sensor. Look for the code on the unit pump.
I have no knowledge of this unit so am reliant on the knowledge of others.
Stephen W Wood: Have had to put my 1007 into a friends garage due to ABS and ESC light being on and diagnosed as ABS pump. This has been changed, but it now looks like the master cylinder has failed!
Neil Gibson: Did they change the valve block? Usually the fault lies with the ecu and the valve block needs no interference. If they changed it then it will need bleeding properly using pp2000 software.
Stephen W Wood: I'm told that the unit was changed and the warning lights have gone out but there is no solid pedal. I'm not overly surprised at that. I think replacing that will solve the problem.
Neil Gibson: My bet is they haven't bled the system properly. Use pp2000 and you can actuate the ABS pump to bleed the valve block.
Stephen W Wood: A pressure bleeder has been used.
Yves De Muyter: The pressure bleeder probably doesn't do the job hence why there is software to open the valves in the abs unit...
Neil Gibson: Correct!