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Viable Option for TPS Replacement
Posted: Thu Jan 22, 2026 9:16 am
by breilly951
Hi all, after following the CARPOKES testing procedures, I determined I need to replace the costly TPS in my 951! Does anyone have any knowledge if this TPS for the older Audis, Bosch part # 0 280 120 431 could be/is a direct fit the Porsche part 951 606 113 00/ Bosch 0280 120 400? While cheaper, it is still a $300 part. Many thanks for your assistance. Bruce
Re: Viable Option for TPS Replacement
Posted: Thu Jan 22, 2026 9:22 am
by gb951
I have experimented with various sensors with the same form factor, and none has turned out to be compatible.
0280 120 400 is only used on some turbo volvo cars, afaik.
Re: Viable Option for TPS Replacement
Posted: Thu Jan 22, 2026 10:07 am
by breilly951
Ok, thanks. I tried to find tech specs for both the original and this one to see what was different/same to determine fit/form/function but was unsuccessful.
Re: Viable Option for TPS Replacement
Posted: Thu Jan 22, 2026 11:02 am
by Tom
This has been on my list for a while... Need to finish the digital timing belt tool first.
Re: Viable Option for TPS Replacement
Posted: Thu Jan 22, 2026 11:12 am
by johnb
I have no idea if this is the case, but if there is one that differs only in the potentiometer value, then we can come up with a custom KLR chip image that's calibrated appropriately. It would still need to have a compatible idle switch of course.
Re: Viable Option for TPS Replacement
Posted: Thu Jan 22, 2026 3:54 pm
by Tom
johnb wrote: Thu Jan 22, 2026 11:12 am
I have no idea if this is the case, but if there is one that differs only in the potentiometer value, then we can come up with a custom KLR chip image that's calibrated appropriately. It would still need to have a compatible idle switch of course.
Does the DME/KLR do anything with TPS other than switch from idle, part-throttle, and full-throttle maps? Is a potentiometer even needed if not, or could it just have three output states -- one for idle, one for part-throttle, and one for full throttle?
Re: Viable Option for TPS Replacement
Posted: Thu Jan 22, 2026 4:15 pm
by johnb
Tom wrote: Thu Jan 22, 2026 3:54 pm
johnb wrote: Thu Jan 22, 2026 11:12 am
I have no idea if this is the case, but if there is one that differs only in the potentiometer value, then we can come up with a custom KLR chip image that's calibrated appropriately. It would still need to have a compatible idle switch of course.
Does the DME/KLR do anything with TPS other than switch from idle, part-throttle, and full-throttle maps? Is a potentiometer even needed if not, or could it just have three output states -- one for idle, one for part-throttle, and one for full throttle?
The DME doesn't do anything other than those 3 states. It can't be cause it doesn't know about anything else. But the KLR uses the potentiometer for various things. Some are related to boost control and so maybe not relevant to a lot of people who use some other form of boost control. But it plays a role in knock control too.
The last thing I wrote on this was
https://jhnbyrn.github.io/951-KLR-PAGES ... ssing.html
I know it's used in the knock routine, but off the top of my head I couldn't say right now what that detection routine will do if the TPS signal isn't present. I'd have to refresh my memory. But if I had to guess I'd say it will still work.
Re: Viable Option for TPS Replacement
Posted: Thu Jan 22, 2026 4:51 pm
by Tom
johnb wrote: Thu Jan 22, 2026 4:15 pm
Tom wrote: Thu Jan 22, 2026 3:54 pm
johnb wrote: Thu Jan 22, 2026 11:12 am
I have no idea if this is the case, but if there is one that differs only in the potentiometer value, then we can come up with a custom KLR chip image that's calibrated appropriately. It would still need to have a compatible idle switch of course.
Does the DME/KLR do anything with TPS other than switch from idle, part-throttle, and full-throttle maps? Is a potentiometer even needed if not, or could it just have three output states -- one for idle, one for part-throttle, and one for full throttle?
The DME doesn't do anything other than those 3 states. It can't be cause it doesn't know about anything else. But the KLR uses the potentiometer for various things. Some are related to boost control and so maybe not relevant to a lot of people who use some other form of boost control. But it plays a role in knock control too.
The last thing I wrote on this was
https://jhnbyrn.github.io/951-KLR-PAGES ... ssing.html
I know it's used in the knock routine, but off the top of my head I couldn't say right now what that detection routine will do if the TPS signal isn't present. I'd have to refresh my memory. But if I had to guess I'd say it will still work.
Sounds good, thank you. I'll stick with a potentiometer then. If I try to come up with a replacement, I'd want it to be functionally the same as the original. Was that page recent? I fear I've missed some of what you've written. We should find a way to post it all on carpokes. You're doing current and future hackers a truly invaluable community service!!
Re: Viable Option for TPS Replacement
Posted: Thu Jan 22, 2026 5:18 pm
by johnb
Tom wrote: Thu Jan 22, 2026 4:51 pm
johnb wrote: Thu Jan 22, 2026 4:15 pm
Tom wrote: Thu Jan 22, 2026 3:54 pm
Does the DME/KLR do anything with TPS other than switch from idle, part-throttle, and full-throttle maps? Is a potentiometer even needed if not, or could it just have three output states -- one for idle, one for part-throttle, and one for full throttle?
The DME doesn't do anything other than those 3 states. It can't be cause it doesn't know about anything else. But the KLR uses the potentiometer for various things. Some are related to boost control and so maybe not relevant to a lot of people who use some other form of boost control. But it plays a role in knock control too.
The last thing I wrote on this was
https://jhnbyrn.github.io/951-KLR-PAGES ... ssing.html
I know it's used in the knock routine, but off the top of my head I couldn't say right now what that detection routine will do if the TPS signal isn't present. I'd have to refresh my memory. But if I had to guess I'd say it will still work.
Sounds good, thank you. I'll stick with a potentiometer then. If I try to come up with a replacement, I'd want it to be functionally the same as the original. Was that page recent? I fear I've missed some of what you've written. We should find a way to post it all on carpokes. You're doing current and future hackers a truly invaluable community service!!
Yes that one was from a few months ago. When I've tried posting these things here, I usually run into issues like formatting tables etc. But it would be good to post things here especially reference info like lists of all the places that each input is used etc.
Re: Viable Option for TPS Replacement
Posted: Fri Jan 23, 2026 9:22 am
by breilly951
johnb wrote: Thu Jan 22, 2026 11:12 am
I have no idea if this is the case, but if there is one that differs only in the potentiometer value, then we can come up with a custom KLR chip image that's calibrated appropriately. It would still need to have a compatible idle switch of course.
So Johnb, for a potential substitute TPS, must the needed values of the potentiometer and idle switch be determined only by testing them or is there manufacturers technical data/specs available of the components which can be used?