EPC light and P164B low oil pressure at high RPM EA888 1.8 2.0 TSI TFSI 4000 RPM limit

Question

With warm oil, at highway speeds, while overtaking, my car turned the EPC light ON on the dashboard and limited my ability to accelerate the engine past 4000 RPM. After turning the car off and on again, the light and the limit dissapeared. Yet with warm oil (more than 90°C aprox) every time I exceded 4000 RPM the error reoccurred.

My car: Volkswagen Jetta Mk6 2013 with 115000 KM (only owner).

My setup: EA888 2.0 TSI, engine code CCZA, 200hp stock engine, front wheel drive, automatic DSG 6-speed transmission.

Answer 1

I was able to solve the problem. This was my experience:

1. I first scanned the car. I already had a scan tool (mine is a genuine HEX-V2 from Ross-Tech):

005707 - Oil Pressure Switch
P164B - 000 - Malfunction - MIL ON
Freeze Frame:
Fault Status: 11100000
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 114184 km
Time Indication: 0
Date: 2018.08.13
Time: 16:44:48
Freeze Frame:
RPM: 4022 /min
Load: 99.6 %
Speed: 129.0 km/h
Temperature: 103.0°C
Temperature: 33.0°C
Absolute Pres.: 1010.0 mbar
Voltage: 13.462 V

2. The engine has multiple pressure switches. On the oil filter housing there's a top blue colored high pressure oil switch that closes circuit between 2.15 and 2.55 bar; and on the bottom a brown colored low pressure oil switch that opens circuit between 0.55 and 0.85 bar. The car onboard computer expects the blue high pressure oil switch to close before 4000 RPM or it will issue a warning and limit your ability to damage the engine by revving it with little oil. Pressurizing the switches with a jig and some sort of air pump while measuring continuity would rule this problem out. I just threw two new original oil switches without measuring oil pressure or switch proper function. In my case, the blue switch was not the culprit.

3. Now assuming the oil pressure was really low at high RPM I did what should have been done first to avoid damaging the engine: I connected an oil gauge. The filter housing has two female M10 fine pitch (x1.00mm) threads that mate with the oil switches. I got an adapter from AliExpress that bolted in place of the top blue high pressure switch and let me connect both the switch and a 1/8" NPT gauge. I wired a hose and fixed the gauge next to my steering wheel. The oil pump has a solenoid that varies the oil pressure. In the high pressure regime, with warm oil, I was just shy of the blue high pressure switch triggering pressure. There was a noticeable change in pressure when revving the engine with low temperature oil meaning the solenoid commanding the high pressure regime was de-energizing correctly and the operated valve working. The change in pressure became less noticeable as the oil temperature increased and the oil pump met it's maximum working power despite commanded oil pressure regime.

4. Following a cheap, likely and easy first list of possible causes, I changed the oil. I had always been using the same full synthetic 5W40 oil and performing all oil and filter changes myself at 7500 km. Always using original filters. The problem persisted. There were no metal shaving in the oil pan, at least nothing other than a small glimmer and one or two sub-mm metal particles. There was no gas smell whatsoever, which could dissolve the oil and make it hard to pump, like when the high pressure oil pump leaks gas into the engine's head.

5. There's an oil filter drain valve, that makes all oil in the filter housing return to the oil pan when the oil filter is unscrewed. You can fish it with your fingers if the engine is cold just below the removed oil filter. If the O-rings on this piece of plastic wear out, the oil can shunt directly from the pressurized oil filter housing to the oil pan and prevent pressure build-up. My O-rings were worn out so I replaced them to no avail. The new O-rings didn't look identical to the thicker original ones, so I ordered one new cheap original oil filter drain valve but that didn't fix it either.

6. High pressure in the carter because of a faulty check-valve in the PCV system letting high boost pressure from the intake manifold at high RPMs go into the engine could fight against the oil pumps work to increase oil pressure. I blew through the PCV hose by detaching it from the intake manifold being careful not to break the connector. My PCV flap check-valve was OK. I also noted unscrewing the oil cap made the engine run a little rough but there was not excessive vacuum nor anything not expected. The bleed hole above the PCV diaphragm did not spit any air suggesting a punctured diaphragm.

7. I removed the timing chain inspection cap close to the harmonic balancer and saw my chain tensioner was both the new iteration and within spec (4 grooves, should be less than 7 on the newer revision). A stretched chain can lead to the hydraulic tensioner going too far out and oil escaping through it, thus lowering oil pressure.

8. I removed the upper portion of the timing cover, used a special tool to remove the left threaded variable timing valve without defaulting to violence with a chisel, removed the cambridge being careful not to lose timing, and found: The variable timing valve was ok. The camshafts journals were not scratched. The metal mesh that filters oil which is inserted into de cambridge fell into the timing section and oil pan as soon as I pulled the cambridge out. The check valve behind this metal mesh filter the check valve was in place. There were no traces of metal mesh clogging oil passages. I reassembled everything without installing any new parts and happy to see the head of the engine appeared to receive oil just fine.

9. I disconnected the variable timing solenoid present on the intake camshaft with the connector visible in the upper timing plastic cover. I never saw any timing errors with my scan tool associated to my low oil pressure, but a failing camshaft which has the variable timing mechanism built into, can wear out and leak the oil sent by the variable timing solenoid and valve meant to vary timing straight into the oil pan, lowering oil pressure. I'm not sure if disconnecting the solenoid should create a timing error on one hand but prevent the oil leakage and confirm a bad camshaft/variable timing mechanism on the other. I tried this approach just in case and the error persisted.

10. I removed the oil pan in my garage prying the gasket maker with a lot of patience and strength over 45 minutes with the nail remover of the backside of a hammer. My car hasn't got any subframe that requires lifting the engine or doing major disassembles. The pickup tube was somewhat clogged, although when I removed it and used water to clean it, it was evident the resistance to flow it offered was next to nothing. The oil pump on the other hand, has complex workings that try to maintain a constant oil pressure regardless of RPM until the onboard computer dictates a high pressure regime, thus saving fuel by pumping less oil most of the time one uses the car at lower RPM. This Volkswagen internal service training document explains everything in detail. By looking to those illustrations you envision a good quality oil pump. The real thing turned out to be full of plastic parts subjected to friction all the time, and any of those parts could wear down and leak. I changed the pump and solved the problem. The chain tensioner was easy to hold with one finger while fighting the pump with the other hand, without any need of timing cover removal (only removed oil pan, oil baffle and pickup tube). Not only did the pressure go from less than 40 psi with the oil at 120°C at 4000 RPM to 53 psi aprox. but I also noted that when turning off the engine the pressure dial I installed went back more slowly to 0 psi, probably meaning the oil pump was leaky and couldn't maintain high pressures with a hot less viscous oil.

Bonus track:

11. I never came across forum posts fixing the issue with a new oil pump. Most revolved around balance shafts. This engine has two balance shafts with 3 bearing each. This shafts spin at twice the RPM of the crankshaft and engine. It seems to be normal for these bearings to fail letting oil go from the pressurized side to the oil pan with little resistance to flow, lowering oil pressure. Damaging balance shafts could maybe raise the engine temperature and be a clue. I guess you could also fish bearing material in the oil pan.

12. My high oil pressure solenoid and valve always seemed to actuate OK, but you could always disconnect the solenoid and see if there's any change in pressure. If the pump is already working at it's maximum capacity, you won't see any change regardless of solenoid and valve working order.

13. A good high pressure switch with good oil pressure could always trigger this fault if there's a faulty oil pressure switch connector.

14. My new pump is "Pierburg", an OEM replacement part. I had the old and new pump next to each other and they are exactly the same castings and quality (but much lower price).

15. I do not know any priming procedure for the oil pump. I only tried filling the new oil after oil pump replacement by pouring it into the oil filter housing in the outer portion. I figured it would return to the oil pump pumping lobes. I'm not sure about this logic either. The engine started without problem and starved for oil for a full second or two before I saw the oil gauge show a proper pressure reading.