Camshaft positioning sensor

My check engine light went on. I took it to the dealer and was told I needed a camshaft position sensor and serpentine belt. They also replaced a side marker bulb and performed a brake fluid flush. $1125 later the engine light comes back on when I drive it home after picking up the car from the dealer. I take it back the next day and they say there are cam correlation faults in the system and suspect timing chains are stretched causing the failure, to the tune of $3700! Had they found this the first time around, I would have never spent the $1125. Does all this sound right?

About two months ago my car just stopped working. When I ran the code it came up code P0340 which is a wire or connector in the circuit could be grounded/shorted/broken the camshaft position sensor may have failed the PCM may have failed there exists an open circuit the crankshaft position sensor may have failed. I wanna know before buying the part if its actually gonna fix it or if it could be something minor.

I have an '01 VW Passat v6 2.8. The engine light is on because of the cam position sensor. The car starts and runs fine. The timing belt was changed about 7 months ago. Is it possible that the sensor itself is sending a bad or no signal?

The actual code is PO348-camshaft position sensor a circuit high bank 1.

Yes it could be the CMP (CaMshaft Position) sensor but, it is also possible the timing belt was not installed correctly, if the camshaft timing is off it will set code: P0348 (VAG# 16732)

Test:
1. Access the Camshaft Position (CMP) Sensor G163 located on the back of Bank 2 cylinder head. (Between the cylinder head and bulkhead.)

A. Pin 1 Red/Black (RO/SW) is a 5 V power source.

B. Pin 3 Black (SW) is the sensor ground.

C. Pin 2 Yellow/Black (GE/SW) is the signal wire. 11 V should be present coming from the Engine Control Module (ECM) to the sensor. While the engine is cranked over (or running) there should be a clean cut square wave patter that drops from 11 V all the way to ground.

NOTE:
Use of the Cam Bar, a (special tool) is required to verify timing belt timing. Once the timing belt has been verified, removal of the valve covers to verify timing chain timing would be required. All timing marks (belt and chain) must line up together.