Code p0502 which sensor should I be looking at and how can i test?

Hello, I'm Danny.

Here is the information you requested. The code is for a problem in the CVT speed sensor circuit. Here is a tutorial showing how to test wiring:

https://www.2carpros.com/articles/how-to-check-wiring

I've attached picture diagnostic flow steps below for your Civic. Let us know what you find and we'll go from there. Hope this helps and thanks for using 2CarPros.

Thanks I did the whole process at some point I didn’t have ground on the ECM connect or C 40 and 44 But. Then I did maybe it’s intermittent
Where is ground g101?
Also this is for the speed sensor on top of the transmission? If the replacement has opposite polarity does that make a difference ?

Hello again.

Here is the information you requested. You will need to replace the sensor with the correct one as to a sensor with reverse polarity will not work correctly. I've attached a wiring diagram and a photo below of the ground g101 you referenced. Here is a tutorial on how to test electrical wiring:

https://www.2carpros.com/articles/how-to-check-wiring

Let us know if you have any further questions on this issue. Hope this helps and thanks again for using 2CarPros.

Danny-

Hi, thanks for all the help it turned to be the short sensor on the back of the transmission, the sensor got scratched up somehow. It has 2 short and two long I replaced it and it worked but eventually the other sensor got damaged also.
What could be causing the sensors to get scratched? And how could I fix this? I will also mention my engine mount broke recently and I’ve been having issues with that
Could a misalignment of the drive train cause this?

Also posting this in case it happens to anyone else because this is my second Civic that had this issue… here is what I would like to share:
The two sensors on the top will give different codes when damaged one is the first one i mentioned P0502 it’s for the short sensor that is closest to the firewall, when this got scratched up or damaged the speedometer quit working at some point the other short sensor which is right in front of it will trigger a code P0796 pressure control solenoid valve C.

Also posting this in case it happens to anyone else because this is my 2nd civic that had this issue… here is what I would like to share
The two sensors on the top will give different codes when damaged one is the first one i mentioned P0502 it’s for the short sensor that is closest to the firewall,, when this got scratched up or damaged the speedometer quit working at some point the other short sensor which is right in front of it will trigger a code P0796 pressure control solenoid valve C

At some point the other sensor triggered the p0796 code when I left the connector off and when I swapped it with the damaged one, the two sensors are interchangeable of same polarity.

Hi,

Thanks for the update and information. I'm confident it will help others.

Take care,

Joe

If anyone can tell me what the cause could be and fix of the sped sensors getting scratched up that would help. I gave a good amount of background info.

Hi,

Sorry, I jumped into the middle of this and thought the issue was resolved. Where is the sensor being scratched? If it isn't an OEM sensor, it may need shimmed.

Could you take a pic of the scratches so I can see what is happening?

Let me know.
Joe