Read the ecu for engine fault codes the other day and this one has come up.

Ive had a look online and it suggests either failed hose going to N75 Solenoid valve, or the valve itself.

Ive checked the hoses going to the valve and all seem fine, is the valve the likely suspect?

The car is mk1 vRS on 109k. with stage 1 remap.

Im going to stick a boost gauge on it later today to see what pressure its getting too.

If I clear this code, it should re-appear on the next run if a mechanical component has failed, if it doesnt does it suggest that maybe the map needs tweaking?

Oh also, if the solenoid valve has failed (or isnt performing to expected standards), could this could a loss of power by the ecu holding back?

Thanks for any help

Edited 29 May, 201115 yr by Squidula

That's strange Stuart, I had the map put on 3 days after buying the car, & it never through a code at all during my ownership.

It's rare for a N75 to fail, but not impossible. You do have to check for splits in the pipes very closely as sometimes they can be very hard to spot.

Ive cleared the code, and its not come back on after a quick drive, might have just thrown a wobbly, my old saabs used to do that from time to time.

Yeah the pipes seem in good condition to me, the solenoid is mechanical so Id imagine itll have a lifespan on it, I might buy one to see if it makes any noticeable difference, theyre only £45.

Could have just been a twitch that the ECU didn't like. I checked the car with vagcom a week or so before you bought it & it was clear. I'll have a look in my garage tomorrow as I might have a n75, if so I'll send it to you.

I cleared this code and it stayed code free for a week or so, checked it on saturday and the same code was back on. Cleared it again, and also took the car out with a boost gauge fitted. Its holding 19psi then trails off further up the rev range as it should do, so I dont believe theres any issue with the map itself causing overboost. I think its unmetered air from a split pipe somewhere. Had a rummage around and couldnt find anything that looks even remotely perished.

What are the common hoses that split and can cause this fault code? Ive looked at the 3 hoses coming from the n75 vavle and they all seem fine, although havent checked the wastegate hose all the way down due to access, Ill have a look at it when I get under the car, I assume access is easier that way.

Since the car is hitting 19psi it suggests the n75 isnt at fault if the car produces the required boost level, unless maybe its sticking and delaying the wastegate opening on occasion causing a very brief overboost?

Did you fit the 007 DV I gave you? If so stick the OEM DV back on, & see if it still happens. The most common pipes to split are the small pipes under the black cover on the inlet manifold, & the 2 small braided pipes, but if any of these are split it usually causes 17705 code so I doubt it's one of those.

Sorry Stuart I forgot to look to see if I have a spare n75 I'll have a look tomorrow