PO720 code (output speed sensor circuit malfunction).
Diagnostic Test Code (DTC) P0720 is defined by SAE J2012 as "Output Speed Sensor Circuit"
Please note that this is a TRANSMISSION CONTROL fault code. If this code was gathered from the Engine Control Module (ECM) with a generic code reader, you are most likely not getting the whole story.
There are several things that can cause this code including:
> Open INPUT speed sensor ground circuit
> Open OUTPUT speed sensor ground circuit
> Damaged ignition wiring
> Open INPUT speed sensor signal circuit
> Open OUTPUT speed sensor signal circuit
> Malfunctioning speed sensor
> Sensor shorted to ground
> Malfunctioning Transmission Control Module (TCM)
Since the input and output speed sensors share the same reference voltage circuit and the same sensor ground circuits, it can be very difficult to determine which sensor or circuit is actually causing this code to set without the proper equipment needed to diagnose this code.
The cost of a new output speed sensor is probably less that one hour of diagnostic time in most areas. So, although I do not believe in replacing parts without properly diagnosing the system, you could probably replace the speed sensor for less that what it would cost to diagnose it.
On the other hand, you must have the required scan tool to access the TCM to clear the code. Please note that a generic code reader may clear the code from the ECM, but the code will still remain in the TCM and can still affect the operation of your transmission - even if replacing the sensor fixes the problem that caused the code to set.
Another problem here is that in order to diagnose this code the correct way, it is necessary to access the TCM to check for other fault codes. There may be several other fault codes present in the TCM that are not shared with the ECM. The path that the troubleshooting chart takes for diagnosing P0720 depends on if there are any other codes present in the TCM, and if there are other codes present...which ones?
I hope you find this information helpful. I wish it were as easy as looking at the code number and telling you what part to replace, but like with MOST fault codes, it simply does not work that way.
P0700....Transmission Control System (MIL Request)
P0720....Output Speed Sensor Circuit
hope this helps
531 views
Usually answered in minutes!
×