MK5 Golf GTI

All Things Mk5 => Mk5 General Area => Topic started by: OllieVRS on April 09, 2025, 11:05:30 am

Title: Bad MAF, reading max value?
Post by: OllieVRS on April 09, 2025, 11:05:30 am

Had this issue for a while now, but need to get it sorted as the old VRS is going up for sale  :sad1: I'll still check in on the forum every now and then to see if anyone needs oil pressure help  :wink:

MAF value on VCDS is reading the max value, no matter it is plugged in or not. Engine is running and pulling like normal, perhaps with worse fuel economy than it should have. Engine light on obviously.

Any ideas?

Cheers

Title: Re: Bad MAF, reading max value?
Post by: lazy on April 10, 2025, 09:43:41 pm

It sounds faulty, as you'd think you'd get a different reading with it unplugged and plugged in.

Title: Re: Bad MAF, reading max value?
Post by: OllieVRS on April 10, 2025, 10:06:03 pm

(https://i.postimg.cc/xC61xxQ2/20250410-135156.jpg) (https://postimg.cc/mzF4hShX)

Faulty, but where? Still reading 5V from first pin on the plug. On a healthy car, what value does it read with the MAF unplugged? Thanks  :smiley:

Title: Re: Bad MAF, reading max value?
Post by: GVK on April 11, 2025, 05:51:29 pm

Have you checked for continuity along the MAF plug?

Title: Re: Bad MAF, reading max value?
Post by: OllieVRS on April 12, 2025, 06:10:48 pm

Thanks for getting back to me.

I've checked first pin, live, is always 5V, the second pin has continuity to negative battery terminal, and the third pin nothing, so I assume data?

I tried getting the ECU out to test too but the annoying b*stard refuses to come out :doh:

Title: Re: Bad MAF, reading max value?
Post by: OllieVRS on April 13, 2025, 04:41:28 pm

5V - 0V -0V. It seems my 12V supply is missing, I'll investigate the wiring back to the ECU. Bit of a pain to take it out the Octavia but anyway

Title: Re: Bad MAF, reading max value?
Post by: OllieVRS on April 13, 2025, 09:27:18 pm

Managed to get the ECU connector out but not remove the ECU. Anti-theft cage in the way and I don't have the right tool to remove it.

(https://i.postimg.cc/hjfFwkN8/20250413-191753.jpg) (https://postimg.cc/Fd5nkBr1)

5V (pin 1 MAF connector) leads to here

(https://i.postimg.cc/WpqL7PGT/20250413-193749.jpg) (https://postimg.cc/K4bHZwpH)

Missing 12V (pin 2 MAF connector) leads here.

(https://i.postimg.cc/L6ddC0Df/20250413-195535.jpg) (https://postimg.cc/dD9SD6zt)

So no issues with the MAF wiring before the ECU. Anything else it could be?

Cheers  :smiley:

Title: Re: Bad MAF, reading max value?
Post by: lazy on April 14, 2025, 10:06:11 pm

I checked mine today in case you didn't have a reference.
Pin 1 5v, pin 2 12v earth, pin 3 12v live.