Fault p0340

Metro

Metro

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Hi guys, I had the cam belt changed by Murran (John) off the forum last saturday, everything went fine, no cam belt errors at all, when I went to the car the next day I got an engine light on... so I drove straight over to my friends to grab his scanner and found fault "p0340 - Camshaft position sensor A - Bank 1 - Circuit Malfunction" Ross tech diagnostic is:

Possible Symptoms
  • Malfunction Indicator Light (MIL) active
Possible Causes
  • Wiring from/to Camshaft Position Sensor (G40) faulty
  • Camshaft Position Sensor (G40) faulty
  • Timing misaligned
Possible Solutions
  • Check Wiring from/to Camshaft Position Sensor (G40)
  • Check Camshaft Position Sensor (G40)
  • Check Timing
Click to expand...
So, I took it to a garage to get the timing checked, which I guessed it wasnt this problem or the light would have come on straight away after the belt was changed, the garage I took it to checked it all over and said they thought the sensor had failed, so, I picked up a new sensor (the hall sensor that sits inside the cam cover. Is this the 'Sensor A - bank 1' sensor? I wasnt too sure!?) and fitted it, cleared the codes and all was fine!

untill... I drove about 150 miles that day without the light coming on, so i thought it had worked! but the next day when I came to drive to work, the light came on after 5 mins of driving... which royaly P****D me off... now, I want to check the wiring to that sensor but im not too sure what values to expect by using a meter or what conditions I should have the car in when checking the sensor?

Would just having the ignition on be sending the sensor power or would it have to have the engine running... also, there are a few wires that go to the sensor, im guessing 1x earth, 2x +/- power and an ECU cable, which one is which?

If anyone can think of anything else that could cause this then could you let me know and ill give it a try! thanks a lot!

EDIT:
murran said:
the cam sensor is a hall effect sensor on the cambelt end of the of the inlet cam. its an ally cap held on with 2 10mm headed bolts, with a three pin plug to it. you should have ones a 5v or a 12v live (cant remember which), ones a ground. the middle wire is the signal back to the ecu.
Click to expand...

Just read this in a PM from Murran so that answers my question on the wires, how do I check them?
 
with a multimeter?
unplug the camsensor plug. put the ignition on, set the meter on volts (20v). put the black meter wire on an earth and check youve got a live (5v or full live) on one of the wires (pin1 i think).
then put the red meter wire on the battery live terminal. check for full ground on the earth wire (pin3 i think).
checking the signal wire (pin 2 i think), ignition off, youd need to unplug the engine ecu. get a wiring diagram to find out which ecu pin number corresponds with the signal wire from the camsensor. or take the cover off the backs of the ecu plugs to find the corresponding wire colour.
set your meter to ohms (resistance), and put one meter wire on one end, the other on the other end, to check the contiuity. i'd expect no more the 0.5 ohms.
 
Are you sure it's not 1 tooth out on the timing? wouldn't necessarily throw a error straight away either, and it seems in both your times it's happened its the next day the code comes up and not straight away. I would check the timing with the crank markings and the cam markings next to ensure it's not that. Sorry Murran not doubting your workmanship but it is a real possibility it could be out 1 tooth..
 
The car drives fine though. And I did mean a multimeter yeah xD and i call myself a techy xD! If it's even a tooth out, say advanced not ******, would it cause damage if the car seems to be running fine? Cheers
 
Wouldnt damage it, and I think some won't even realise it was a tooth out! I'm not saying for one minute it is but it's certain worth considering, and it's very easy to chech, line up the marks on the cam wheel and cam covet and make due the timing mark on the crank, through the little viewing window is lined up as well. The only way I have found 100% to ensure correct timing is to mark the old cambelt to the camshaft and the cambelt to crank, transfer those marks to the new cbelt and you will always get correct timing. If you did this then it's likely to be the hall sensor or wheel.
 
pfft, im just going to put up with the light to be honest, Ive checked it with a multi-meter and it all seems to be fine... what wheel are you referring to? Cheers
 
ive personally got these a tooth out at work. last one was a bam tt about 5/6 years ago. im not kidding when i say i must have changed 40+ 1.8t timing belts on tts/a3s/a4s/a6s since then without issue.

on that tt, within a minute of running it came up with "p1340 cam/crank sensors incorrect assignment". while it ticked over ok, on driving it, it felt really flat and struggle to rev over 2500rpm.

toms says its running as well as it did before?
 
Then it's unlikely to be the Cambelt, but it will depend if it's advanced or retarded though. Honestly though before you go chasing anything check the timing marks, it's easy and quick and I'll tell you if it's the belt, if the fault had popped up any other time I wouldnt even mention the belt, but the day after? It's got to be worth checking , if not for peace of mind.. Eliminate not speculate......
 
Had one do the same a few days ago, x reg PD115 AJM audi a6, ex taxi- 300k on the clock. The owner gave it some beans and it jumped timing. It was throwing the same code but the car would not start. Got a new sensor and no change, unplugged the sensor and still no start then proceeded to strip the cambelt and the gap on the damper was too big- audi specifies 4mm. Timed the engine and presto- it's started first turn of the key !
 
Check the syncro angle in VCDS block 4 and see how tight the belt is, if over -3/3 then it's out. have seen them running at over that but the power and fuel consmption were not there... Get-it as close to 0 as possible...
 
adamss24 said:
Had one do the same a few days ago, x reg PD115 AJM audi a6, ex taxi- 300k on the clock. The owner gave it some beans and it jumped timing. It was throwing the same code but the car would not start. Got a new sensor and no change, unplugged the sensor and still no start then proceeded to strip the cambelt and the gap on the damper was too big- audi specifies 4mm. Timed the engine and presto- it's started first turn of the key !
Click to expand...

on the 1.8t lumps the tensioners not the same as the pd tdi engines. 1.8t has a similar damper to apply tension and damping, but the center on the tensioner is not eccentric/adjustable. so you cant get that bit wrong like you can with the diesels.
 
im so confused right now xD as murran can tell you all, Im clueless when it came to the cambelt. not sure what to do first! this is where i wish i was a mechanic!

edit: clueless when it comes to most things on my car!
 
well im sure its timed up correctly, and you said youve dropped it into a garage local to you and theyve said its timed up correctly.

agreed i cant ignore the fault having come up the day after the belt was changed, but the fact that its running as well as it was before rules out a misalignment of the belt.

only thing i can think of is the jacking up and down of the engine (which, as you saw 1st hand, you have to do in the course of removing the drivers side engine mounting bracket) has stressed/damaged an already weak wire within the loom from the engine to the car.

what were the results of the wiring checks you carried out exactly?
 
Last edited:
Well.. It was dark so i didnt check the ECU wire, but I held the multimeter (got it this time) to terminals 1 and 3 and got a reading of 4.8 v (and what ive read is that it is a 5v line) so im pretty sure thats within bounds for making sure its got power. As for the ECU line, I will check that tomorrow if I have time, got loads of uni work due for monday so ill try and procrastinate (lol) and get that one figured out
 
worst comes to worst and I cant figure it out, ill drop it round to the manufacturing dept where I work which is full of electronics geeks and chuck them the car for them to nosey over... I want them to make me some heavy duty earth lines too so they can do that at the same time
 
I am wondering though, for instance, if there is a bad connection somewhere and every now and then the connection is lost... will the light come on and chuck the fault code, and also, if the connection is made again, will the light go off or will the fault code remain?

The only reason I say this, is because I can reset the code and it will come back as soon as the car is restarted (e.g yesterday morning) or it can stay off for the day before it comes back
 
while its running, if it looses the cam signal, even for a couple of seconds. the fault will be logged, management light will come on and stay on, even if its not present for the next journey the fault and the light will remain till its deleted.

the engine ecu is under the cover beneath the wiper scuttle panel. the wiper arms and the panel itself need removing to get good access.
the ecu is bang in the middle to the n/s. it slides out of its mounting bracket to the o/s.
 
drive it back up to me if you want. i'll recheck the timing and if nessasary remove the whole wiring loom and physically check it as per the wiring diagram.


*edit* i might regret the statement offering the above..... but i dont like anyone thinking ive not done a job correctly, and the offer stands.

but if it all checks out ok id have no where to go but suspect the ecu itself.
 
okay, ill reset the codes tomorrow, tape the multimeter to the pins and give the cables a bit of a wobble for as far as i can trace them, see if the light returns! and keep an eye on the multimeter ofcourse. If I can put it down to a wire then ill splice it and replace it. If i cant find it then ill just ignore the light untill I can get a propper electronics nerd to check it out... if that fails and the problem cant be found, then.. god knows what im going to do :)

It past its MOT a few days ago with no advisories so ive got a year to sort it :p
 
mot.... if the physical timing was out, no way would it have passed an emissions test. i would have thought the 02, lambda and hc's would have been a mile out?
 
cool. anyway.............................................................. its half 1, im going to bed!!!!!!!
 
ditto!

edit (again lol): emissions were spot on by the way, I asked about them and he just pointed to the paper he gave me... ill get the readings tomorrow if your interested?
 
Okay, I left the battery unplugged for 6 hours today hoping the car would forget the code completely after i erased it... Now it's coming back straight away on the reader but not on the cars dash.. I'm really confused now! It used to clear it for a while but now it doesn't. Starting to pull my hair out now!
 
Have you checked the timing marks? I've suggested this a couple of times, if you eliminate this you'll have something to diagnose
 
I'm going to have to look into how to do that, I'm pretty clueless, will I have to take all the fuel lines off to see everything or is there an easier way?
 
Remove timing cover from driver side if engine, rotate engine, easiest way is to jack up car, put into gear and manually turn wheel to turn engine and line up the mark on the cam pulley with timing mark on cam cover. Then remove the small plastic bung from top of gearbox, in front of gear selector and check the timing mark is in the middle. Make sure you don't have the engine running! And no need to remove any pipes etc, you just need a torch.
 
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