My Trebeca sent an ABS code and my mechanic replaced the rear ABS sensor. 3 days later after driving through some slush for ½km the light came on again.

Any ideas?

clean out the entire knuckle/wheel/axle area and make sure it's not due to debris between the sensor and reluctor ring.  debris on the ABS sensor can cause issues.

 

check code again and make sure the correct one was replaced. 

 

aftermarket wheel bearings cause ABS sensor issues ocassionally - has the wheel bearing on that wheel ever been replaced? 

 

maybe the new sensor is bad - check it's resistance or continuity per the FSM. 

Thanks for your quick response. Unfortunately my mechanic has reported back that the code is for the opposite sensor that was replaced. Coincidence? I don't know. I guess I cannot complain at 230,000km and many miles of gravel roads.

Edited December 28, 20169 yr by GordH

Subaru ABS sensor issues aren't common and they routinely last the life of the vehicle, having more than one fail is strange. 

 

I have seen them degraded and warn down significantly - either due to the elements (winter, salt, treatments) or road debris, I'm not sure.  I would guess it's due to rocks or salt/chemicals. 

The sensor has been blown free of any and all debris and the code cleared. We will hope that is the only problem. Is there any record of electrical problems or specific connections that have caused problems in the past that you are aware of or any other sources of false readings.

The sensor was cleaned yesterday and the code cleared. It was driven out of te shop and parked with no problem. It sat outside at -6ºC ( 21.2ºF) overnight and when started in the morning the ABS and AntiSkid lights came on and remained on.

I know I have a tire pressure sensor that goes on when frozen and off when the tire warms up. Possibly the same problem? We will try crimping the connections next week to see if that works.

Thanks for all your ideas and Happy New Year.

Update.  The Trip Odometer now says "ER SS". we took the connections to the sensor apart and cleaned them but the code now shows the sensor as "Open". A new sesnor has been ordered.

This must go down in history with both sensors self destriucting in a metter of weeks.

Anyhow thanks for your input and best regards for 2017