Citroen C5 Gearbox Fault - Crank Sensor?

[pd2444]

Hi all,

Car is 2008 (X7 model) C5 2.0 HDI with the 6-speed AM6/TF80 gearbox.

It has done 140k miles but generally goes OK.

However, since I've been driving it over the last couple of months I have noticed the odd weird shift pattern. I don't mean it slips or clonks or does other things a failing valve body on these gearboxes (which I am familiar with!) usually does but that the car its self will sometimes put it into 6th at 45mpg and sometimes you can enter a motorway and it'll stay in 5th at 70mph for ages unless you manually select 6th in which cases it changes just fine.

However, yesterday with the car still quite cold I came to a stop and it cut out. I re-started and pulled away but once it got to 3rd gear I had the "bong of doom" and Gearbox Fault on the dash and the gearbox was in limp mode. I stopped and restarted and all was fine again.

I have had a look at the codes and the gearbox error code is P0727 which apparently relates to no engine speed information. A bit of further research says this can also lead to weird shift patterns.

There is also a code in the engine of P0337 which relates to crankshaft position.

Am I right in thinking these are both related and the gearbox gets its info from the same place?

I presume the first course of action is to try a new crank sensor? Has anyone had similar faults/codes which have been caused by this?

Thanks.

[Stickyfinger]

Do a forum search on oil changes .....they say this box is sealed for life however that "life" seems to be for the lease market eg: 100-120k miles.

They respond well to a good couple of changes over a short time period so an change would be my first call. (ONLY USE the oil from a Dealers)

[myglaren]

However, yesterday with the car still quite cold I came to a stop and it cut out. I re-started and pulled away but once it got to 3rd gear I had the "bong of doom" and Gearbox Fault on the dash and the gearbox was in limp mode. I stopped and restarted and all was fine again.


There is also a code in the engine of P0337 which relates to crankshaft position.

If the engine stalls it will record a crankshaft sensor fault but when restarted it will remember that, at least for a while but not put up an EML.

As Mr. Sticky says, the gearbox oil may well be the source of your problems - known issue with them.

[bobins]

Don't shoot me down, as I'm working from distant memory here, but do differing tyres / tyre circumferences cause odd problems with these gearboxes ? I seem to remember people having odd problems related to differing tyres across axles but can't remember if it was with this gearbox and whether it caused odd changes (as per OP) or ESP/ASR issues....... or none of the above

[Hell Razor5543]

Certainly some automatic gearboxes and ABS/ESP systems can be confused by different tyres (even between makes supposedly of same sizes) as the tyres (if they have differing circumferences) would then have different spin speeds.

[GiveMeABreak]

Don't shoot me down, as I'm working from distant memory here, but do differing tyres / tyre circumferences cause odd problems with these gearboxes ? I seem to remember people having odd problems related to differing tyres across axles but can't remember if it was with this gearbox and whether it caused odd changes (as per OP) or ESP/ASR issues....... or none of the above

Are you referring to this post - seems an almost identical issue:
http://www.frenchcarforum.co.uk/forum/v ... ce#p496615

[pd2444]

I think it definitely could do with an oil change but I think the reason for it going into limp is, at the moment, an electronic one rather than mechanical.

The code the gearbox stored was "Engine Speed signal incorrect value received". I presume the engine gets that signal from the crank sensor then sends it to the gearbox?

As they don't appear to be much money I will try a new crank sensor then look at an oil change. Next question: where exactly is the crank sensor on these cars - are they gearbox or cambelt end?

Thanks for all replies so far.

[jgra1]

Will try and have a look tonight at crank sensor as have an engine lying about..
Will do and oil change on mine soon as i can too.
2.0 hdi 125,000
John

[pd2444]

Well, found it. Pretty easy really - take off the driver's side front wheel and you can see it. It reads off a reluctor behind the crank wheel - one 10mm bolt and it comes off.

Have put a new one on and no stalling or gearbox errors thus far.

[aeroboy64]

Well, found it. Pretty easy really - take off the driver's side front wheel and you can see it. It reads off a reluctor behind the crank wheel - one 10mm bolt and it comes off.

Have put a new one on and no stalling or gearbox errors thus far.

Hi sorry to reply to an old thread but as i'm having the same problems with my gearbox did the new sensor cure the problem?My box stalls and goes into limp mode (3rd gear) and after restarting all is fine (comes up gearbox fault and makes a hell of a noise).
Thanks in advance for any replys.

[pd2444]

The crank sensor certainly cured the stalling issue (or, at least, seems to have done) and stopped the gearbox going into limp mode after the car was restarted.

As for the reluctance to change up - top marks to the posters who said check the tyres. The tyres were Michelin Primacy all round so looked identical but 3 were 101 load rating and one was 97 (on the back). I took the 97 off and put the spare on which was a cheapy non brand tyre but 101 load rating. Viola - completely different gear pattern above 40mph.