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C4 - DS4 Owners :: Forums :: Coupe and Hatch Pre 2011 cars :: C4 The Garage

C4 Engine sucking air from oil cap Error Codes: P0087 / P1338 / P1336 / P1340

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Wed Apr 08 2020, 10:09pm
Member No: #55905
Joined: Apr 08 2020
Location: Auckland
Hi – a bit of strange problem and running out of thoughts. Some ideas please please~~~

Owning a 2012 C4 Executive 1.6 Turbo (EP6 engine) since new, so its about a bit more than 8 years old. Nothing major happened during its life. Small oil leaks, Some coolant leaks, but all at acceptable level. Has had about 5 times in its whole life that the gears have gone wrong. You put into gear, but nothing happens – the car doesn’t move, the gear is not engaged. I suspect it is just computer glitch. If you turn the car off for 10-15 minutes, waiting until the actuator of the gearbox resets, and everything goes back to normal. No engine fault light in this either. More likely to happen, when you turn the car off when it is in gear, I found.

Anyway, back to the main topic. A couple of weeks ago. The main issue came in. One day when I drove normally, I noticed when loss of power. Lucky I wasn’t too far from home and when I parked up, I noticed the fan went on full speed for some time. Next day, I turn the car on and the engine fault light came on straight away. And gave me FOUR error codes from my ODB reader:

P0087 Fuel Rail / System Pressure Too Low
P1336 Crank / Cam Sensor Range / Performance
P1340 Camshaft Position Sensor B Curcuit Malfaunction
P1338 No Description (Manufacturer Controlled Code (Non-Uniform DTC) )

The car started, but the fan went straight to full speed (when the car was still cold), the engine was shaking, like there was a misfire.

The strangest thing (I have never had before) is the engine is sucking air from the oil cap. When the engine is running, you will notice a clear noise coming from the oil cap, and there is a vacuum. It is hard to undo the cap, because the air keeps going in from the cap. You can still feel the air is going through the air intake, but not much. The shake of the engine almost felt like the engine is suffocating.

I swapped the spark plugs and swapped the coils, the codes remained, and nothing changed.
I undid the breather hose, and vacuum pressure from the oil cap got better, but you can hear the air is sucked in from the breather hole.

Because there are so many things that could go wrong, I am running out of thoughts. I believe the vacuum behind the oil cap is the main symptom of this fault. Should not be there, but not a mechanic and cant say for sure. It doesn’t happen to my other cars.

btw, engine oil is normal, gearbox oil was replaced about 3 years ago, and there is a video I uploaded at the time anyone who wants to do it:

- Click Here -

Any thoughts please please? Thanks!!!

Thu Apr 09 2020, 03:01am
Member No: #574
Joined: Jul 08 2007
Location: Dorset
Try removing the air filter. effectively a petrol engine is an air pump. The inlet phase tries to suck air into the engine. Normally this would be via the inlet system, but if it is blocked it will try to suck it in via the route of least resistance. There should be some suction via the oil filler as it is necessary to remove and burn off oil mist.
Thu Apr 09 2020, 05:15am
Member No: #55887
Joined: Apr 05 2020
Location: Oop Norf
I would firstly carry out a BSI reset, Google the procedure. This will eliminate the behaviour of the fan and the odd fault codes, which to be honest don't really match the issue of drawing air from the oil cap.

The suggestion of disconnecting the air filter makes sense, but I can't think of a reason the intake path could block, unless you have a cotton filter in there and it has broken up or been soaked with oil and has clogged up solid. Did you put a performance cotton filter in and has it been oiled recently? Over oiling these can cause issues.

Anyway, did the engine run normally when you managed to remove the oil cap or continue to run rough?

A collapsed intake tube between filter and the turbo intake could cause this, if it's prior to the point where the pcv valve connects to it.

Start by resetting the BSI module and see what faults or issues remain.

Next, open up the air filter and check the paper or cotton elements haven't disintegrated or blocked up with dirt.

Then, see if the tube from the filter to turbo is not blocked or collapsed.

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