My 175k 2020 1.5 TSI broke down on Friday. The AA bloke got it going by cleaning the number 1 spark plug of oil and using easy start but it was running rough and I left it with my mechanic. I had various codes for

• P0087 - Fuel rail/System pressure too low

• P0171 - System too lean (Bank 1)

• and one for seized coolant pump B

I thought the codes pointed towards a failed fuel pump but since the plugs had oil I think now it points towards a poor fuel/air ratio.

There had been a bit of oil consumption recently so I replaced the PCV which didn't solve it. So now I'm thinking either

• turbo seals as there's a fair amount of oil in the pipework

• piston rings which are notorious on these engines

• valve stem seals

Does anyone have any experience of similar. If it's the turbo it is fixable but piston rings mean it's a goner.

Edited Monday at 06:465 days by gm73

3 hours ago, gm73 said:

so I replaced the PCV which didn't solve it

Is the new PCV installed correctly and is it a good or genuine one. If a cheap ebay rip-off it may still be letting alot of oil past

3 hours ago, gm73 said:

since the plugs had oil I think now it points towards a poor fuel/air ratio.

More likely oil entering combustion chamber.

3 hours ago, gm73 said:

cleaning the number 1 spark plug of oil

Oil or soot? If Oil, then its probably not the poor fuel ratio, maybe the poor AF ratio and injection codes are a symptom of Oil getting onto the O2 sensor

If it was soot, then its all about the AF ratio

Has the cylinders been examined for bore scoring? as the 1.5tsi uses a special plasma coating on the cylinder walls and if that is damaged the engine is basically toast.

@wiilydog , sad to say that I've just seen that YouTube video about that issue, ie after roughly 80,000miles expect it - horrible!

Quite a history of issues up to this.

How much engine oil is being used?

Have a compression test done on engine.

Just back from the garage.

Full boroscope inspection done and a wisp of oil in cylinders 1 and 3. Everything as normal otherwise, no scoring.

Also compression test done and only cylinder 3 was slightly down but still within tolerance.

Small amount of oil in turbo intake pipe but turbo boosting properly.

Mechanic says there is excessive suction at the PCV despite a new one being fitted and he can't get his head around it. He's phoning a VAG specialist friend tomorrow for his opinion on where to start with that. He says that is where the oil consumption will be happening.

New spark plugs fitted and the car seems to be driving better than before. He says the ones in the car were well past their replacement due date. They were only 60k miles old as well!!!!

So hopefully it's not piston rings or turbo.

They were, by 20,000 miles. The schedule is 4 years / 40,000 miles on the spark plugs. I would say especially with a 1.5 TSI ACT 40,000 miles is long enough before replacing.

Could be failed turbo seals and oil is ending up in intercooler plus being burnt . Check its not full of oil. Had similar on old volvo. Seals failed and was burning oil and intercooler was pretty full. Used to smoke like mad after idling for a while.

Alasdair

Small update. Spent today driving it and it’s certainly not 100% as it’s hunting on start up before settling down and there’s a bit of additional vibration in the cab at idle. (There always was a bit but it’s worse). There’s also a bit of a whistle noise which would certainly indicate a leak somewhere, possibly the intake manifold which may be causing the excessive suction in the crankcase.

Here’s what it’s doing on start up

I think a leak in air intake manifold would reduce suction in crank case but it could be a blocked breather pipe think goes from engine to PCV? I think there is a one way valve inline.

Alasdair

52 minutes ago, Alasdair1 said:

I think a leak in air intake manifold would reduce suction in crank case but it could be a blocked breather pipe think goes from engine to PCV? I think there is a one way valve inline.

Alasdair

The mechanic is currently stumped as to why there’s excessive suction. You’d hope he’s checked the breather pipe but you never know. I’ll take it off and have a check myself.

On one of my old cars there was I think a non return valve which was gummed up. Hopefully its that simple.

Alasdair

Edited Wednesday at 15:102 days by Alasdair1

On 29/07/2026 at 16:10, Alasdair1 said:

On one of my old cars there was I think a non return valve which was gummed up. Hopefully its that simple.

Alasdair

The car was getting me down a bit this week as there was hesitation in 2nd and 3rd, vibration in the cab from an uneven idle and the issues on start up.

I was messing about with the pipes and took the one pictured off and put it on again and everything has went back to normal. The car is responsive and you can’t even hear it running.

No idea what I’ve done, perhaps cleared an airlock or in typical mechanic fashion they’ve maybe not put the pipe back on again properly and there’s been an air leak.

Thank goodness for that.