1G 1g VSS leaking internally?

Anfurnyy · Jul 7, 2026

Got an issue I've been chasing for a few months now. My speed sensor on the transmission is leaking.

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I've got a Brantz speed sensor adapter for my link g4+ ECU. Should be irrelevant?

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I've already replaced the o-ring with a non-oem but it was the same size and it still leaks. It looks like it's leaking from inside the speed sensor itself as the speedo rod is also covered in oil. Not sure if there's more seals inside the sleeve that's seal off the actual rod/ gear but I can't get mine disassembled to find out.

I have a new OEM o-ring and new sleeve coming from STM but also looking for any advice / if someone has one they wanna let go. I'll make a post in classifieds as well

DSMPT · Jul 7, 2026

There is a small oil seal for the driven gear shaft inside sensor housing. Most likely that's the cause if the key slot on the shaft has oil. Also you should make sure the breather is not clogged, if it's clogged, it would build a good amount of pressure and would leak from weaker seal location even seals are still working.

Anfurnyy · Jul 7, 2026

DSMPT said:
There is a small oil seal for the driven gear shaft inside sensor housing. Most likely that's the cause if the key slot on the shaft has oil. Also you should make sure the breather is not clogged, if it's clogged, it would build a good amount of pressure and would leak from weaker seal location even seals are still working.

Thanks! I did check out amayama and found that seal in the diagram. I'll also check my breather as well. I recently put on on it in the nearby port and honestly it almost seems like that's when this issue started..

DSMPT · Jul 12, 2026

Little late but sharing it here for further search, future reference anyways.
The diagram taken from the FSM. #4 is the seal.

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1G 1g VSS leaking internally?

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