CEL P0500 Vehicle Speed Sensor Malfunction

[travisb]

During installation of new wheel studs, I was working on one side of the car and my dad on the other. For some reason he took the stainless ring off the axle and when he put it back on, it was backwards.

After putting everything on and doing a test drive the CEL, ABS, and Slip indicator came on.

The ABS sensor on the rear-left was damaged by the ring that was on backwards, rubbing against each other. The bottom half of the sensor was worn down and bending outwards.

I got a used sensor off of Ebay from a highly rated seller, "verified" to be in working condition. I installed it yesterday, with the ring in the correct position.

The error lights are still on. I've cleared the error, reset the connection in the trunk, disconnected battery, etc. multiple times. I inspected the sensor and cables and everything looks great.

I did contact the Ebay seller but I have not heard back yet. It is the weekend.

Before I take it to the dealer, what are some other things I can check?

[steve99]

Originally Posted by travisb

During installation of new wheel studs, I was working on one side of the car and my dad on the other. For some reason he took the stainless ring off the axle and when he put it back on, it was backwards.

After putting everything on and doing a test drive the CEL, ABS, and Slip indicator came on.

The ABS sensor on the rear-left was damaged by the ring that was on backwards, rubbing against each other. The bottom half of the sensor was worn down and bending outwards.

I got a used sensor off of Ebay from a highly rated seller, "verified" to be in working condition. I installed it yesterday, with the ring in the correct position.

The error lights are still on. I've cleared the error, reset the connection in the trunk, disconnected battery, etc. multiple times. I inspected the sensor and cables and everything looks great.

I did contact the Ebay seller but I have not heard back yet. It is the weekend.

Before I take it to the dealer, what are some other things I can check?

is the sensor ring damaged as well

[travisb]

Originally Posted by steve99

is the sensor ring damaged as well

Sensor ring? Not sure what part that is. I replaced the entire sensor assembly from the wheel hub section to inside the trunk.

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[Ultramaroon]

The ring that your dad installed backwards is the sensor ring (aka reluctor). The speed sensor needs to accurately sense the rotation of that part. Is it damaged?

[travisb]

The part that was installed backwards was the "outer joint assembly baffle" labeled "8" in the diagram below. That piece was a little bent up but I straightened the edges back up and rotated it to face the correct direction.

I am not sure which part is the sensor ring. I don't believe we got that far into the axle while removing the wheel hub to replace the wheel studs.

[travisb]

Can someone post of picture of the sensor ring? I don't remember seeing it and I cannot find any BRZ/FR-S pictures online showing it.

[Ultramaroon]

I searched to no avail (I mean really searched for a good hour) before replying. Even the service manual does not mention anything about a rotor/scale/reluctor. What does the business end of the speed sensor get close to? Can you take a photo?

[travisb]

This is a photo I took the other day. These are the two holes for the sensor. The sensor drops down the larger hole and a screw holds it down in the other one.

The silver you see at the bottom of the hole is the baffle that was installed backwards.

So the sensor hangs directly over and next to the baffle. Perhaps the sensor reads the splines on the axle.

[steve99]

Originally Posted by travisb

Sensor ring? Not sure what part that is. I replaced the entire sensor assembly from the wheel hub section to inside the trunk.

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yep their might not be a separate ring but the sensor must use something as a pickup you say it might be axle splines make sure their clean and not full of dirt\grease is their any adjustment on sensor ?

If you have techstream it can read outputs from individual wheel sensors

not sure you will see any voltage change if you measure with voltmeter as you slowly rotate wheel, maybe compare to working sennsor.

[Ultramaroon]

The service manual makes a big deal of making sure the sensor is clean. I think that baffle serves double duty. If you look at photos of the front hub, it also has a similar looking rotating part attached to the inside.

http://www.frsport.com/Subaru-28373C..._p_398295.html

[travisb]

Here is some additional information. When I start the car, the CEL, ABS, and Slip indicator are all on. When I clear the CEL, it goes out, but the other two lights stay up, and about 5 seconds later the CEL is back on. This is without the car moving.

There is no adjustment on the sensor. It looks as clean as the other one. It is not caked in mud or anything. The splines on the axle looked fairly clean if I remember correctly.

The fact that all the lights turn on when the car is not moving, even after clearing the CEL, is confusing me. Maybe the new-used sensor is bad. Or when the old sensor was damaged, could it have hurt the VSC computer or blown any fuses? I checked the green ABS fuse and it looked ok. I could not remove the second, smaller ABS fuse. I did not have anything to grab it with earlier.

[Ultramaroon]

After seeing your pics in the wheel stud thread, I'm sticking with my guess about that ring. I hope an expert chimes in.

[sstfnv]

The exact same thing happened to my friend's BRZ. When replacing the wheel studs somehow the ring damaged the sensor and the ring got bent pretty bad. In his case we just bent the ring back to its original shape as much as we could though the hole of the ABS sensor using a screwdriver and installed a new(used) sensor from ebay.

You can either straighten out the ring or replace it. The ring part number is 28437FG000.

[steve99]

They may be toothed rings or maybe the new magnetic type which will be smooth, you may have the encoder ring on backwards or the sensor is stuffed.

Above photos not from BRZ