How to sort out an ABS fault in a 2002 Peugeot 406


The 406 Passed its MOT test recently, and the day after it passed the test i got the ABS light on, i plugged in the PP2000 to find out that the issue was with sensor for the Right front wheel.
Removing this wheel allowed access to the ABS sensor, the sensor is a magnetic device which generates a signal for the ABS module when the teeth in the reluctor ring pass it, this allows the ABS module to know the speed of each wheel of the car and if it detects a wheel is going too slowly i.e. skidding it will quickly remove the braking to that wheel.

In this case the sensor got dirty after an mot wash, and old dried flaky rust appears to have been drawn straight to the magnetic head of the ABS sensor, this then interferes with the reading on that sensor and causes the car to show up a fault and deactivate the whole ABS system.

The danger of not having functioning ABS is that when you apply the brakes hard, the wheels will lock and start to skid, any steering inputs will not change the cars direction during a skid which makes it uncontrollable. With ABS the control of the steering can be maintained during heavy braking, and the wheels do not enter a skid as the braking effort is automatically pulsated between being on and off by the ABS.

Although i did use a Peugeot planet (or PP2000) machine in the video, it is possible to attempt to fix an ABS light without any diagnostic machine, however knowing the exact sensor causing the problem saves a great deal of time. I tried to test the ABS sensor with a multimeter, but I'm not 100% sure if my technique works any comments on that would be appreciated. The PP2000 has a parameter measurement for the speed of each wheel which tests the sensors much more reliably than a multimeter.

Thankfully i did not need to change the ABS sensor on the 406, in some cases if you get a snapped spring the wiring may get cut, changing the sensor is quite a simple procedure, i show in the video how to remove the sensor from the hub, and how to disconnect its plug, the only unseen process is the grommet where the wire from the sensor passes through the suspension turret into the engine bay. Replacement sensors can be taken off cars in a scrapyard, however new ones are relatively inexpensive.

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