Camshaft Sensor Error (P0340)

[Kaput]

Hi folks,
Recently got the car (Vec SRi 1.9CDTi 120, 55 plate) MOT'd and serviced (including timing belt).
When i collected it from the mechanic guy that does my MOT's the spanner light was on and it turned out to be the P0340 error. After consulting with one of his friends at a Vaux garage the guy was told they suggest changing the camshaft sensor when doing timing belts so he changed the sensor (lot of work apparantly).

Car was fine until Wednesday this week when the spanner light came on just after starting up and the car ran a bit crap but after a mile the light went off and car drove fine. Was no issues on Thursday but then today the light came back on for less than 5min while idling in the drive.

Starting to wonder if the battery or alternator are on the way out. Using the test thing on the CD30 computer/stereo the voltage was 11.something before starting the car on Thursday but went to 14.0/14.1 while cruising down the bypass at 70 (dropped to around 13.9 while driving slower around town though).

Any thoughts/ideas/suggestions? Car has chewed through £700 odd already this year and it was in better condition before its service :/

[Critch]

Check glow plugs

[rich r]

When they changed the camshaft sensor, did they fit a genuine Vauxhall/GM one? I (and many others) have been through often months of pain on Z18XE (1.8 petrol) Vectras when non-GM ones have been used by garages to save a few pennies. After being one visit away from returning my car (and having already drafted letters to the garage and my solicitor) following dozens of times of them adjusting the sensor and changing it's wiring and other things, they decided to try a genuine sensor. And all the problems went away - it's been fine for 25,000 miles since.

Something to check anyway.

[Kaput]

Think its a pattern sensor since Vauxhall wanted about 3 times the money for it compared with the motor factors he got it from. Due to how much the car has cost this year alone i probably can't afford a genuine one plus the inveitable cost of fitting it. Should probably point out the guy that does the work on the car (and has done work on most of my cars) just does it as a little side job from home.

As for the glow plugs, can they be tested without having actually change them for potentially pointless new ones?

[Kaput]

Been out in the car today, slow starting but no warning lights. Ran fine.
Test mode on computer showed battery at 12.1v before starting and straight to 14.1v after starting.

Checked the battery itself and found the negative terminal wasn't exactly properly tightened, would that cause these sort of troubles?