Leon OBD fault occurring at 16.8 v

**beeroclock** · 26-09-2022,01:51 PM

Hi all
I am getting a fault occurring and glow plug light flashing saying intermittent fuel pressure low.
When I look at the freeze frame of the fault occurring I notice that the voltage at the time at terminal 30 is 16.8 Volts.
This surely cant be right.
Could this high voltage play havoc with the OBD sensors, etc?
If so what could be allowing this high voltage?
many thanks for looking
Nigel
2010 Leon II 1.6 cdi ecomotive. CAYC engine2022_09_22_from waynes diagnostic_01.jpg

**Crasher** · 26-09-2022,04:47 PM

If it really is hitting nearly 17v a number of the controllers will shut down, do a full vehicle scan and post the result.

**beeroclock** · 27-09-2022,09:10 AM

Thanks for that Crasher.
I cant get access to the diagnostic until next week so the full scan will have to wait.
What do you mean by IF it is really hitting17v?
For now lets say it is, what could cause it?
many thanks

**Crasher** · 27-09-2022,09:46 AM

IF meaning it may not be but probably is so that would point straight to the alternator.

**beeroclock** · 27-09-2022,10:28 AM

Ahh interesting. OK, thanks
Do you think that if the voltage is 17v (in fact when we scanned it last time the voltage on fault occurrence was 17.8v) and the sensors are shutting down it would throw a code and send the car into limp mode?
Many thanks

**Crasher** · 27-09-2022,03:26 PM

When I am using ODIS the dealer system, the car has to be on charge, you have to keep an eye on the permanently displayed "line 30" voltage as if it creeps up to 15v or above, many controllers shut down and store a "function limitation due to overvoltage" code so yes, 17.8v could really **** of a controller.

**beeroclock** · 27-09-2022,03:35 PM

Ok thanks again. So I had better start searching for an alternator!! I know they are not cheap, the car has stop start.
I post on how it went.
thanks again for your help
Cheers

**beeroclock** · 27-09-2022,03:51 PM

Quick question if you dont mind. How important is it that I fit a stop start alternator? They seem to be the same amperage.
Would it damage anything if I fitted a normal one?
cheers