Limp mode with multiple fault codes

Feb 4, 2023
6
0
Hello all,

I'm new to the forum and wondered if anyone has seen this problem before.

The car is a 2018 150 Leon FR 2.0 diesel.
There are 5 fault codes which are on permanently:

1. Transmission neutral position sensor - implausible signal
2. Sensor reference voltage C - open circuit
3. Sensor for internal pressure of cylinder 3 - electrical error
4. Turbo/supercharger underboost
5 Transmission neutral position sensor - electrical malfunction

The car goes into limp mode randomly, usually within a couple of miles into the journey.
We replaced the #3 glowplug sensor last week. The code for that cleared initially, but is back

The car apparently has a long history of this fault going back three years.

Any help would be much appreciated.

Thanks in advance


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adam davies

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Dec 30, 2019
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Is the car dsg or manual. I would possibly try seeing if the neutral position sensor is working correctly using diagnostics vcds or obd eleven. Found this link could be the problem. If the values are move onto one of the otger errors.
 
Feb 4, 2023
6
0
Thanks Adam.
It's a manual but it's also faulting the #3 glow plug, which was replaced last week, and the turbo underboost.
It had the same faults in 2020. Glow plug #3 sensor replaced. Fault continues.
 

adam davies

Active Member
Dec 30, 2019
338
138
Forgot the link. https://www.google.com/amp/s/www.op...al-gear-sensor-implausible-signal?hs_amp=true.

When you replaced the glow plug and the fault came back that would suggest the glow plug itself is not at fault. Check wiring to glow plugs and compare voltages to working ones. If that checks out you possibly have and internal engine problem.
Also check the link above about neutral position sensor
Thanks Adam.
It's a manual but it's also faulting the #3 glow plug, which was replaced last week, and the turbo underboost.
It had the same faults in 2020. Glow plug #3 sensor replaced. Fault continues.
 

DTR

Mar 5, 2023
1
0
Hi I've got a 15 plate 2.0 tdi leon fr 184, I have the cylinder 3 glow plug fault code, bought a new glow plug and that hasn't come back up but I have a fault p02990 turbo underboost. Car is constantly trying to regen, its on 152k, done a bit of testing swapped n75 valve for a know good one same issue, carried out forced regen and cleared most of the soot, same issue, looking at live data, when flat out its asking for 1300 something, forgot the unit, and the turbo is only giving 900-1000. Bit unsure I believe it could be the actuator, got a vacum pump on order to test everything. Just after a bit of advice. Thanks. Dpf ash mass value is roughly 60 grams so I know the dpf is near the end of its life but just trying to rectify the lack of power first. Engine does rev freely so dpf isn't completely blocked solid.
 
Feb 4, 2023
6
0
Thanks for that. Sounds like you know what you're doing more than I did!
Luckily for us, the dealer agreed to swap the car as we'd only had it for 2 months. He's got an UP Gti now.
All the best for your troubleshooting/rectification.
 
Jun 5, 2023
5
1
I recently had my new leon go into limp mode. There were 2 fault codes, but both were general and not specific fault. The temperature gauge went into the red. But were I checked the header tank there was no loss of water, also no steam, and once the electric fan stopped I felt the radiator and that was not hot. I presumed the water bypass valve had failed. My Seat dealer replaced the whole water pump assembly. Has anyone else had this problem?