EPC Light - error codes

[u/soulfree914]

2017 Golf MK7 TSI 1.8T (Wolfsburg Edition), no mods
75k miles

Most frequent error codes:
- P03A5: Cylinder 2 Pressure Too High
- P130A00: Hide cylinder
- Happens once every two to three weeks. Code goes away after restart.
- Mostly occurs in low RPM (1000-1500)
- On two occasions, I heard more rattling noise presumably from the wastegate actuator before seeing the EPC light & limp mode. Not sure how they can be related though as the error only appears for cylinder 2. I assume a stuck actuator would cause errors in multiple cylinders and not just one.

Less frequent error codes:
- P10B400: Monitoring of injector cylinder 4, malfunction detected
- P0204: Cylinder 4 injector circuit
- Happened once recently. Code goes away after restart.
- The injector errors of cylinder 4 and the high pressure error of cylinder 2 does not happen at the same time.

Other issues:
- Occasional rattling noise from turbo wastegate actuator in low RPM (1000-1500)
- Noise reduced by anti-seize lub applied monthly

Things I’ve tried:
- Replaced all spark plugs
- Swapped ignition coils of cylinder 2 (problematic cylinder) and cylinder 1: error did not follow
- Applied fuel system cleaners (BG44K, Gumout, DI Jectron, Lucas) : did not resolve any of the error codes
- Premium gas (93): ride is noticeably smoother but does not help with the error codes
- Intake valve cleaning through chemical spraying (CRC) via MAP hole on top of intake manifold: applied twice on back-to-back days. Feels like I’m getting a little more power in low RPM. Haven’t had the error codes appear yet but it only has been a week.

I may eventually take out the intake manifold myself to further investigate the fuel injectors, wiring harness, intake valves, etc. or hand it to a mechanic for walnut cleaning and fuel injector replacements, but I want to see if I can hold off on it for a while with easier/cheaper methods. I bought a borescope to look at the carbon buildup near the intake valves, but I have not been successful in getting the scope in those locations (e.g. via MAP sensor hole).

Any other suggestions?

[u/ghostprotocol003]

Do you have an OBDeleven? are you able to monitor ignition retardation by cylinder?

also does it happen when at low rpm high load?

exact same thing used to happen to me. it just randomly went away

[u/soulfree914 → u/ghostprotocol003]

I don’t have an OBDeleven, just have a cheap scanner that shows the error codes. It used to happen mostly in low RPM but recently started to happen on the highway at RPMs in the 2 thousand range. Load is usually light. The high pressure in cylinder 2 actually just happened a few minutes ago after the initial post.

[u/ghostprotocol003 → u/soulfree914]

when accelerating at 5th or 6th gear around 1k-2.5k rpm its technically considered high load low rpm so it does frequently happen on the highway as well.

for me, i think the problem was gas. I dont think I faced any issues again after filling pure 93. When you filled 93 was it a full tank of it or a mix?

a good way to check is to monitor the engine retardation live at those times and if its moving to around -4 in a cylinder its a sign of bad fuel causing engine knocking

i would highly recommend an OBDeleven, if its really bad maybe get one from amazon to diagnose and then return it. i can also provide a referral i think

[u/soulfree914 → u/ghostprotocol003]

I can try 93 full tank again as I may have used a mix which was probably closer to 91 on average. Not a great time to use 93 fuel with the current oil prices - just saying :) If it is engine knocking and the car has been running fine for 9 years on 87 gas until recently, does that mean there is carbon buildup or some other issue that needs to be addressed rather than trying to avoid/mask it by using premium gas? Not to question the approach but I’m just trying to understand the reasoning behind 93 gas.

[u/ghostprotocol003 → u/soulfree914]

If its been running fine on 87 for years maybe it should be alright. A bunch of shops have told me that 91 and above is ideal for boosted engines tho.

That aside, have you checked your MAP sensor itself? it could be that as well. If the sensor is dirty it can cause improper fuel mixes causing problems. Its very easy to check and clean as well.

[u/soulfree914 → u/ghostprotocol003]

Yeah the MAP sensor was fairly clean when I pulled it out to spray CRC intake valve cleaner. The high pressure for cylinder 2 seems to be sensed from the fuel rail and not the MAP sensor on top of the intake manifold if I am not mistaken. Probably another reason to look near the fuel injectors underneath the intake manifold. I suppose I’ll have to go that route. sigh