C5 X7 ES9A 3.0 V6 - P1335 low power

[Zosski]

Hello everyone,

Since January this year I'm owner of C5 X7 with 3.0 liters gas engine.
When I bought the car it had decent power - comparing to today situation.

Feburary 2026 - timing belt was done -
my friend said that on intake cams you cannot set it exactly as it should be since those engines do not have adjustable cam gear comparing to ES9J4S (I attached pictures how they were set comparing to marks)
DAYCO was used: https://motostacja.com/p/155053.html
April 2026 - rear camshaft cover was sealed

Somewhere around June just of curiosity I wanted to check what's the power of the car so I did dyno run - it came out about 180 HP and 220NM!

We've connected the diagnostic tool and only two errors were there:
P0021 - Position of crankshaft sensor rear cylinders - discontinuous error - it disappeared after cleaning errors
P1335 - Position of crankshaft sensor unknown, front and rear cylinders - permanent error - it keep coming back.

Those errors were never observed before - since I last check while changing the automatic gearbox oil end of May.

What have been done together with my friend:
-We check the signals from sensors (crankshaft + camshafts sensors) to ECU - they seem to be fine.
-We check the signals from sensors using oscilloscope however we lack knowledge if it can be an issue - it seems like rear camshaft is late (Camshaft angle offset) ~2 degrees comparing to front camshaft sensor data.
I attached images - seems that in exported images we have issue with high voltage but it was there in actual software (just missing in pngs).
CH1 is either crankshaft or camshaft front (Depends on image)
CH2 is always camshaft rear

Whenever P1335 is deleted it comes back after few seconds or minutes of idle or riding
VVT solenoids stop working at some point + crankshaft/camshaft synchronization says NO in the program, camshaft stays fluctuating around 35-37* and the P1335 is back.

Next thing we want to do is to at some point check solenoids of VVT and do oil pressure test.

It would be great if you have any advice or can give us opinion on data we collected using oscilloscope.

[mickthemaverick]

What year is your car?

[Zosski]

It's 2009 and about 118k miles right now.

Other than not working VVT while P1335 is there I don't have any other issues with it.

[Zosski]

Since my last post the problem hasn't gone away — it's actually worse.
After clearing P1335, the VVT now doesn't work at all, right from startup. Before, it would work for at least the first 2–3 km of driving.

The only thing I've changed since last time is ultrasonic cleaning of the VVT solenoids.

New measurements
-We scoped it again. The waveforms haven't changed much, but this time I got much better quality captures — attached.

I've also gottwo documents that may help:
-The PSA diagnostic sheet for P1335
-A drawing of the reluctor ring, showing the sensor axis position with the engine pinned. Posting it in case it's useful to others.
If you need it PM me.

-And a link to what looks like a correct waveform for this engine, though I can't confirm it: https://rotkee.com/en/waveform-library?engine=2244

Plan for the next 2–3 weeks:
1. Pull the covers and check the intake cam target wheel positions against the drawing + seal some oil leak in nearby areas.
2. Check the dowel pins between the VVT sprockets and the camshafts, plus the sprockets themselves.
3. Verify the belt timing was done correctly.

If all of that checks out, we'll try advancing the camshafts one tooth on the belt — our readings and the marks from my first post suggest they're currently retarded.