Cam position sensor faulty?

[wiffers]

Hello guys. I have an A4 B7 with 3.2 v6 FSI (UK RHD). It has the engine management light on. My VCDS cable is broken, so I used a mate's machine and it read the following:
P0341 - Camshaft position sensor (G49), implausible signal
P0021 - Bank 2: Camshaft A (intake) retard setpoint not reached (over advanced)
P0346 - Camshaft position sensor (G163), implausible signal
P0087 - Fuel rail/system pressure too low.
The symptons are very intermittent, the car will seem to have low power at high RPM when under load. When static or low revs i's fine. One minute it works, then it doesn;t. And Ive had it slightly weaker (10%) but the light just wont come back on.
I reset the codes and had on tick over, all fine. Then I revved the engine and immediately P0346 (Camshaft position sensor (G163)) comes up. I can repeat this. So my hunch is this is the one causing the issues.
When I had my VCDS a few months ago I noticed a camshaft sensor warning, reset everything (as wasn't dated), but nevrr re-checked as cable broke. This is the first I've heard of the fuel issue, so unsuire of separate or linked.
From what I've posted above, it is likely it's one of the G163 sensors and others have a knock on effect.??
Thanks

[OliNix]

If it is ok at idle and only comes up under load or at high rpm my first port of call would be check the timing belt/chain. Under no load it would be fine but as things speed up they are probably stretching/untensioning flagging the fault.

[wiffers]

Since posting I've seen audi specialist who says the implausible message suggests sensor as chain usually different message on same sensor

I'm swapping sensors as easy, then will look at chain and tensioner. You could be right, but I hope not lol

This is very intermittent though, I can drive hard for half hour and it's perfect.... Would that be typical with chain?

Thanks

[OliNix]

No, if chains any hard driving would flag the fault as the tensioner basically collapses and the change in tension creates more slack, changing the cam position. So if you can drive hard with no faults then it is likely the sensor.

[wiffers]

No, if chains any hard driving would flag the fault as the tensioner basically collapses and the change in tension creates more slack, changing the cam position. So if you can drive hard with no faults then it is likely the sensor.

Yeah, it's a weird one

Trying to show mechanic other day with warm engine, drove hard for 20 minutes with nothing. Then could JUST feel a difference at 4k ish when booting it.

Yesterday had to use car, cold engine drove couple of miles. Started off fine, then when it warmed up it was a little bad. Coming back a couple of hours later perfect, so drove extra 20 min, and still perfect.

This morning cold engine, low revs low power bad. Then suddenly worked like normal again.

It's completely intermittent. That's why I'm hoping it's the sensor.

But most of the time I can drive normal or boot it fine. I'd say it's only bad 10% of the time if that.

Fingers crossed eh?