Jrichards75

I have a high mileage R series I bought for my kids to drive. I replaced the wheel sensors and now I'm getting the Malfunction light. I reset the codes with my scan tool after changing them. Initially I got error with all 4 speed sensors. Does it take a while for the car to learn the new sensors or is there a calibration I need to do? I did buy the sensors off Amazon, but they matched the OEM sensors exactly.

I"m learning as a MB home mechanic. I appreciate your help.

streborx

It takes about 15-20 minutes of driving to ensure sensors have been read, but there's also a calibration reset function. After the tires have been inflated to the pressure you want, calibration sets the inflated pressure as the reference point. Check your owners manual for info on accessing the calibration menu.

Jrichards75

Thank you. I appreciate the feedback, but I'm talking about the wheel speed sensor. Is there a calibration for them?

streborx

Not that I'm aware of. What was the fault/malfunction that required the speed sensors to be replaced?

Jrichards75

My scan tool showed implauseable values the two rear sensors so I bought a set and changed them all out. After changing them I had all 4 wheel sensors showing the same thing. I reset the codes thinking it was just from the change out, but the malfunction dialog box came up this morning when my wife was driving the car.

With all 4 showing the same issue now I wondered if there is a recalibration or reset procedure to get the computer to learn the new sensors. All connections were tight and all sensors were installed correctly. This wasn't a hard changeout compared to some of the repairs I've done.. Just don't know what's wrong other than somehow the sensors aren't correct for some reason.

Thanks,

John

streborx

If the connectors are only 2 wires, then the sensors merely send a variable frequency pulse signal proportional to the wheel speed. Were the connector seals still tight, and was there no evidence of corrosion on the contacts? The mounting usually does not require any adjustment. If you have an ohmmeter, you might check the resistance of the old sensors and the new sensors to see if there's any difference.

Jrichards75

That's a great suggestion. I will ohm out the sensors. They are two wire sensors so they are just sending. The connectors all looked in good order. No loose wires or indication of water damage.

I'm wondering if I just got some bad check China sensors. This is a budget build car so i bought the sensors on Amazon versus FCP Euro.

Thanks again for the suggestion. I appreciate the response.

abercanadian

Did you resolve the issue yet?

Larry

Jrichards75

Yes! Evidentially the car just needed some time to recognize the new sensors and recalibrate. After the initial light it went back off about 50 miles later. Code scan has no issues with the sensors so evidentially all is good. I bought a second set of sensors just in case, but never needed them.

abercanadian

ok! just bought a set myself. we'll see how it goes!

streborx

Glad to know this worked itself out. Can't think why a simple reluctance sensor would need some sort of calibration or setup time. Were you receiving any notifications regarding ABS or traction control inoperability, or only the check engine light?