2015 oil pressure switch and limp mode

cobdr

Member
Joined
Nov 22, 2021
Location
TN
TDI
2015 Passat TDI SE
Issue: When the engine is cold (temp qauge less than 80f) it takes very little throttle to cause limp mode and flashing GP light, no other lights. Key off, key on and it’s cleared. Once warm it’s flawless. Each time limp mode is triggered it sets a code for the oil pressure switch. I don’t know the code yet, it still at the shop.
It’s actually at its second shop and each has changed the switch out without change. Both shops are reputable and somewhat stumped at this point. VCDS logging doesn’t show anything out of order. They’re going through the wiring at this point but I’m not hopeful.

A little searching here and I’m nervous about the oil pressure. 1) I read the oil pressure switch doesn’t kick in until 2000 rpm (about when limp mode occurs), and 2) oil pump and hex shaft are potential failure points.

Thing is they oil pressure light never illuminates so I’m not sure it’s an oil pressure problem.

I’m tempted to cover my bases and have the shop replace the pump and hex shaft anyway, one of those better safe than sorry things. Maybe put in a manual gauge as well just for the peace of mind.

Car has 85k miles on it, full delete done around 70k with Malone tune done by the shop that has it now.

Any thoughts, validation or otherwise, are greatly appreciated. I’ll probably be getting it back unsolved if wiring or oil pump don’t work and I’m not sure where to go next.

Thanks,
Bob
 

DivineChaos

Top Post Dawg
Joined
Jul 27, 2019
Location
Minnesota
TDI
mk6 jetta sportwagen tdi
Issue: When the engine is cold (temp qauge less than 80f) it takes very little throttle to cause limp mode and flashing GP light, no other lights. Key off, key on and it’s cleared. Once warm it’s flawless. Each time limp mode is triggered it sets a code for the oil pressure switch. I don’t know the code yet, it still at the shop.
It’s actually at its second shop and each has changed the switch out without change. Both shops are reputable and somewhat stumped at this point. VCDS logging doesn’t show anything out of order. They’re going through the wiring at this point but I’m not hopeful.

A little searching here and I’m nervous about the oil pressure. 1) I read the oil pressure switch doesn’t kick in until 2000 rpm (about when limp mode occurs), and 2) oil pump and hex shaft are potential failure points.

Thing is they oil pressure light never illuminates so I’m not sure it’s an oil pressure problem.

I’m tempted to cover my bases and have the shop replace the pump and hex shaft anyway, one of those better safe than sorry things. Maybe put in a manual gauge as well just for the peace of mind.

Car has 85k miles on it, full delete done around 70k with Malone tune done by the shop that has it now.

Any thoughts, validation or otherwise, are greatly appreciated. I’ll probably be getting it back unsolved if wiring or oil pump don’t work and I’m not sure where to go next.

Thanks,
Bob
Easiest thing is to put an analog pressure Guage on it. Start when cold, and watch. So on a cold motor, when the oil is really thick you get a low pressure fault, but not when it's hot?
And the hex shaft is known for failing....

Well you'll know for certain manually checking oil pressure. Sounds like the pump brive may be slipping when cold. Not sure if that's whats happening. Just my theory..
 

cobdr

Member
Joined
Nov 22, 2021
Location
TN
TDI
2015 Passat TDI SE
Easiest thing is to put an analog pressure Guage on it. Start when cold, and watch. So on a cold motor, when the oil is really thick you get a low pressure fault, but not when it's hot?
And the hex shaft is known for failing....

Well you'll know for certain manually checking oil pressure. Sounds like the pump brive may be slipping when cold. Not sure if that's whats happening. Just my theory..
Thanks, I feel like I’m on the right track at least
 

cobdr

Member
Joined
Nov 22, 2021
Location
TN
TDI
2015 Passat TDI SE
To close this out. We hooked up a mechanical oil pressure gauge and pressure is fine as suspected because the idiot light never came on during this entire event.

Turns out there is a 2nd oil pressure switch that none of the shops (including dealer) were aware of. It’s a little hard for me to fathom that the diagnostic flow didn’t identify it but hey it’s resolved and I’m very glad for that. Especially given the way fuel prices are going right now.

Bob
 

Taff786

New member
Joined
Feb 19, 2023
Location
Blackburn
TDI
Audi A3
To close this out. We hooked up a mechanical oil pressure gauge and pressure is fine as suspected because the idiot light never came on during this entire event.

Turns out there is a 2nd oil pressure switch that none of the shops (including dealer) were aware of. It’s a little hard for me to fathom that the diagnostic flow didn’t identify it but hey it’s resolved and I’m very glad for that. Especially given the way fuel prices are going right now.

Bob
Hi bob
I’m having the same issue with my car… it’s showing oil pressure switch fault. I believe you said there were two switches?!? Where is the other one? Thanks in advance
 

cobdr

Member
Joined
Nov 22, 2021
Location
TN
TDI
2015 Passat TDI SE
I’m not 100% sure since the guys at MF Auto did the work. It’s been a while but I recall the tech saying it was hidden from plain site but not hard to access near the upper rear side. The service manager may remember if you give them a call. He drove my car for the best part of a month and we talked a couple times a week during that time. Super nice people and easy to talk to. Black Passat with black and beige interior. If you’re not far from Knoxville stop by their shop, it wasn’t an expensive fix.

I don’t have the car anymore to go snooping around myself. Sorry I couldn’t be of more help.

Bob
 

740GLE

Top Post Dawg
Joined
Aug 19, 2009
Location
NH
TDI
2015 Passat SEL, 2017 Alltrack SE; BB 2010 Sedan Man; 2012 Passat,
def will be interesting to see if this crops up as another common issue as the miles pile on.
 
Top