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Subaru Speed Sensor Questions

The speed sensor indicates the speed at which a vehicle is moving and acts as the information hub for vehicle handling and brake systems. In some vehicles it also provides communication for the transmission to shift. Because of the various functions it performs, a speed sensor is a critical part in a vehicle. Read below where questions about speed sensor problems and the answers that have provided by Experts.

If a Subaru Tribeca shows a PO 500 fault, how can the 4wd speed sensor be tested?

The PO 500 code relates to both front wheel speed sensors. The only way to definitely know which sensor is faulty is to have it checked with a scan tool. It could also be the wiring or tone ring, but whatever the problem, the scan tool will help take out the guesswork.

On a Subaru Legacy, the fan works only when moving, could this be the speed sensor?

If something is shorting so the relay loses ground when the vehicle is stopped, this gives the impression that the fan is linked to the speed sensor. Trace the wire from the relay and look for a short.

Could a bad speed sensor cause the speedometer and cruise control to stop working on a Subaru Forester but the ABS light is OK?

There is no definitive answer to this problem unless the speed sensor is checked with a digital oscilloscope. An oscilloscope will read exactly what the sensor is doing and present the result in a waveform on a screen. Speed sensors do fail at times but in this case it would appear that the problem is with the speedometer. Sometimes when driving if you whack the dashboard it wakes up the speedometer and gets it working again. This is an unconventional solution which often works. If it does it is a faulty speedometer which needs early attention.

Could a Subaru vehicle speed sensor affect the dashboard lights?

Generally there is no connection between the two. If the dashboard lights behave erratically it could be because of a bad ground in the electrical system or a faulty connection in the instrument cluster.

The AT Temp light flashes on a Subaru Forester, and the on board diagnostics retrieves codes 24 and 33. 33 relates to the speed sensor which is OK. What is code 24?

Code 24 relates to the transfer clutch solenoid which is likely to be stuck in the open position. In this position fluid pressure is applied to the transfer clutches which will cause the car to bind when taking a tight turn. On the passenger side under the hood look for a small box marked FWD. Insert a 10 amp fuse there which should resolve this problem.

Why would parking on a steep slope cause all a Subaru Outback's sensors to flash. The error message initially read ESS which changed to err IU.

ESS suggests that one of the speed sensors for the ABS is malfunctioning which is why the ABS light has come on. When the check engine light comes on the cruise control light also comes on. This is a safety feature so there is nothing wrong with that. Err IU which it has switched to, indicates low battery voltage. All this points to a problem with the battery or charging system, both of which need to be checked. If it is a bad speed sensor you can continue to run. If the battery does not charge for whatever reason, the car will stop as soon as it drains completely. All other symptoms are suggestive of a faulty speed sensor. The problem has nothing to do with being parked on a steep slope.

All vehicles with ABS brakes have four speed sensors located near each wheel. These send continuous pulses to the on-board computer. Resulting in response to which the braking circuit is appropriately operated. For all speed sensor problems consult an Expert before making changes which are not needed.
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