Can anyone help me?

I have a Mk1 Octavia with a 1.8T AUM engine.

I’ve been having a ‘P0172 System Too Rich Bank 1’ code pop up.

i delete it and it only comes back months apart. thought nothing of it at first but popped up a few times recently.

I’ve been down a rabbit hole on Google AI which has diagnosed my Air Mass sensor as needing replacement. It has come to this conclusion from me sharing the freeze frame data of the codes plus some live data that i got from the code reader at acceleration, 70mph and deceleration.

I am aware to not fully trust what AI has told me so I thought i’d come on here to see if anyone has any ideas.

Just gonna chuck in a few pics that show the data screen that has rpms, speed, long term fuel trim and MAF

IMG_8168.heic IMG_8407.heic IMG_8404.heic IMG_8387.heic IMG_8397.heic

Rich codes that only turn up every few months are usually something that sticks or leaks some of the time, rather than a sensor that's dead. Worth ruling out the cheap stuff before buying a MAF.

1. Oil level and dipstick. Check the oil isn't overfilled and doesn't smell of petrol, and that the dipstick is pushed fully home. Both are on the Ross-Tech list of causes for this code and take a minute to check.

2. N80 purge valve (the charcoal canister valve in the engine bay). If it sticks open it feeds fuel vapour into the intake when it shouldn't, and that comes and goes. Simple test: with the engine idling, pull the electrical plug off the N80 and feel the canister side hose. There should be no vacuum. If there is, the valve is leaking. You can also pinch or plug the hose and see whether the fuel trims come back towards zero.

3. Fuel pressure regulator. On the AUM it sits on the end of the fuel rail with a small vacuum hose. Pull that hose off with the engine running. If it's wet with fuel or smells of fuel, the diaphragm is split and it's pushing fuel straight into the intake.

4. Coolant temp sensor. If it reads colder than the engine really is, the ECU adds fuel. Compare the coolant temp in live data with what the dash gauge shows once it's warm.

5. Injectors. A leaking or dribbling injector can do it, especially on a car that's done a lot of miles.

If you can, post the long term fuel trim at idle and at a steady 2,500 rpm, warm. If it's mostly rich at idle, the things that matter most at low airflow (purge, regulator, a leaky injector) are favourites. If it's rich across the range, that helps narrow it down too. Also save your pics as jpg, as .heic won't open for a lot of people on here.

1 hour ago, SparePartAlam said:

Rich codes that only turn up every few months are usually something that sticks or leaks some of the time, rather than a sensor that's dead. Worth ruling out the cheap stuff before buying a MAF.

1. Oil level and dipstick. Check the oil isn't overfilled and doesn't smell of petrol, and that the dipstick is pushed fully home. Both are on the Ross-Tech list of causes for this code and take a minute to check.

2. N80 purge valve (the charcoal canister valve in the engine bay). If it sticks open it feeds fuel vapour into the intake when it shouldn't, and that comes and goes. Simple test: with the engine idling, pull the electrical plug off the N80 and feel the canister side hose. There should be no vacuum. If there is, the valve is leaking. You can also pinch or plug the hose and see whether the fuel trims come back towards zero.

3. Fuel pressure regulator. On the AUM it sits on the end of the fuel rail with a small vacuum hose. Pull that hose off with the engine running. If it's wet with fuel or smells of fuel, the diaphragm is split and it's pushing fuel straight into the intake.

4. Coolant temp sensor. If it reads colder than the engine really is, the ECU adds fuel. Compare the coolant temp in live data with what the dash gauge shows once it's warm.

5. Injectors. A leaking or dribbling injector can do it, especially on a car that's done a lot of miles.

If you can, post the long term fuel trim at idle and at a steady 2,500 rpm, warm. If it's mostly rich at idle, the things that matter most at low airflow (purge, regulator, a leaky injector) are favourites. If it's rich across the range, that helps narrow it down too. Also save your pics as jpg, as .heic won't open for a lot of people on here.

Thank you for this. Also, note taken on the images :) I shall look into those suggestions. I think the code usually appears after a longer drive or heavier acceleration (after meaning it’ll pop up after this once it’s been at idle or on 30 roads for a few mins). But I would still say a bit sporadic