Few hundred miles after 55k service, now I'm getting a CEL for Knock Sensor

[r1de]

Pulled the codes this morning, just knock sensor high intermittent. Now I think I'm not just imagining slight loss of power at idle & different engine noise, though it's pretty subtle and running okay. Odds that it's just the sensor (maybe not torqued right or something) versus something more serious? Okay to run it another day or two before digging in?

[bman005]

I'd wanna know wanna know whats goin on. Especially if you think you're noticing a noise and power loss

[Paulito]

could be bad gas.

[r1de]

CEL went out this morning. Will check it out more closely tomorrow and post a followup.

[airbornerifleman]

Do you have an aftermarket intake? Is it hot where you are? It could be heat soak creating pre detonation. I have the same issue in the summer. I just got a custom heat shield from blinktek, I hope this helps for next summer. The funny thing is that I had the custom intake setup for the last 4 summers and this summer was when I got the CEL and such.

[CorneliusRox]

toss some isoheet in the tank. Tis the start of the season for water in fuel

[r1de]

Can't find anything wrong with it and the light has stayed out. Power/sound are normal. So I guess it was just bad gas or water in the fuel.

[r1de]

Can't find anything wrong with it and the light has stayed out. Power/sound are normal. So I guess it was just bad gas or water in the fuel.

Update: so the light came back on again, and the dealership was able to diagnose it: the rocker arm was misaligned. This apparently happened during a previous repair I had for an oil leak that occurred as a result of a previous repair I had for the cam follower/cam replacement. So it's a sordid journey. No cost to me for the repair since it's a Mea Culpa on the part of the dealer.

So now I'm wondering... will having the rocker arm misaligned for a while cause any damage to the cam?

[bman005]

Did they tell you which rocker arm it was? Just curious

[r1de]

Did they tell you which rocker arm it was? Just curious

I don't have the paperwork yet and don't remember for sure, but I believe it was for cylinder #3 and one valve that they were going to replace. However, I got a voicemail today that they won't be done with it until Friday now, and apparently will also be replacing the HPFP. So that will be cam, follower, rocker arm & at least one valve, plus the HPFP... like getting a new motor.

I'll followup here when I get the paperwork and car back.

[bman005]

Ask them if your car qualifies for the PCV extension, intake flap motor , or the low pressure fuel sender warranty extension. Audi just upped coverage on them to 10/120,000 miles on certain vehicles (Mine has all 3!)

[r1de]

Quoting the paperwork:

"FOUND FAULTS FOR MISFIRES ON ALL CYLINDERS P0300, P0301, P0302, P0303, P0304. AND P2294 FOR HIGH PRESSURE FUEL PUMP CONTROL CIRCUIT. THE VEHICLE SOUNDS LIKE A DIESEL. DIAGNOSED WITH HELP FROM FOREMAN. REMOVED SPARK PLUGS AND USED BORE SCOPE AND CYLINDER WALLS LOOK GOOD. REMOVED HIGH PRESSURE FUEL PUMP AND FOUND THE FOLLOWER HAS WORN THROUGH AND THE PUMP IS SCORING INTO CAMSHAFT. NEED TO REPLACE INTAKE CAMSHAFT AND HIGH PRESSURE FUEL PUMP. [...] REPLACED VALVE, LIFTER AND ROLLER. REPLACED INTAKE CAMSHAFT, HIGH PRESSURE PUMP AND FOLLOWER. [...] OIL CHANGE TO REMOVE ANY METAL DEBRIS."



So basically I had the following things replaced:

Cam + gaskets, filter
HPFP + follower
Rocker arm + valve

Car is running noticeably more strong and smooth...

One thing I'll say is that my dealer got my back on this because it was all done under no charge, even though the car is out of warranty. This was because the possibility (read: probability) that it was necessary due to an improperly replaced cam first time around.