C5 X7 not starting (again)

[DickieG]

I'd put the cooling fan and suspension triggering speed anomaly faults down as spurious faults as I repeatedly get them on mine and they don't affect the operation of the suspension or cooling fan. Most cars have various faults you'll see on almost every example you test, the important lesson here about diagnostics is knowing what to ignore and what to take seriously.

On that note I'd investigate the brake contact signal and rear height sensor fault by reading the parameter screens and operating the brake/suspension and noting whether they respond to actuations and/or re-appear after the car has been driven.

I'd look to take the turbo pressure regulation and flowmeter signal fault's more seriously (just in case the turbo is being back pressured - will knacker it quickly) by carrying out further investigation, firstly by driving the car for a few miles to see whether they re-appear and secondly by observing the data stream on the parameter screens when the vehicle is being driven. With regard to these two faults and whilst not on a Citroen I have come across similar faults on Volvo's, BMW's, Audi's and Fords where the cause has been down to a misbehaving EGR valve, (normally blocked to some degree) or turbo actuator valve which upsets the expected flow of gases through the engine as written in the software.

As for these faults possibly being the cause of the non start issue I can't see it personally but then again depending upon who wrote the software something silly like the brake signal fault could be upsetting the BSI or engine ECU and is it simply down to a misplaced switch as in not physically secure or faulty or is the brake signal fault symptomatic of something else such as a poor earth? Nonetheless even though you don't have Lexia with you try testing the brake switch with a multimeter or even fitting a new one as IIRC they aren't expensive, do fail and so is a cheap place to start.

Overall more questions than direct answers for you I'm afraid but best to drive it for a while then have another diagnostic session and then see what has/has not been logged and then read the parameter screen's whilst carrying out actuations etc. On that Note I'm happy to have a look for you at some point, plus if nothing else I have basically the same car to compare it with.

[qprdude]

Final three photos. Tyre pressure sensors fault(s)

[DickieG]

I know that my knowledge with Diagbox is minimal, but what I hoped to do was to find any faults (if any) that would not clear, as I felt that these were most likely to be relevant. There are, in total, three. Rick has already posted one, there is another in the Suspension tab (which suggests that something isn't getting a speed input), and the other is in the TPM system (well, there are two here, one is speed related, and the other is a non responsive sensor, that won't say what pressure it can see! Bit weird, this one, as Rick advised me the O/S/F has an issue, but, according to Diagbox, the N/S/F isn't talking).

The TPMS showing on the wrong wheel is simply that when the sensors were programmed the wheel with the faulty valve was in a different position so what is now the O/S/F wheel used to be the N/S/F etc, that's why I marked my wheels on the inside after I programmed them so that I can always put them back in the same position after a tyre change

[vborovic]

that's why I marked my wheels on the inside after I programmed them so that I can always put them back in the same position after a tyre change

Blasphemy! ... where's the fun in that ...

[qprdude]

The Turbo pressure fault did not return after clearing, and after a few miles drive. The third screenshot in each case, shows the final check, and what faults remain.
The front tyres were changed in February this year but the rims were put back on the correct side. The monitors were changed FOC by Citroen in 2013, and have been OK since then, until the tyres were changed. Both fronts have shown "tyre deflated" on occasion since February. I took the car back and had them check , remove and re-seal the offside tyre. A short time after, the nearside tyre showed "deflated". Neither tyre was what I would consider badly underinflated (around 2 PSI) and unless the sensors are super sensitive, I can only assume that National tyres have managed to damage the monitors. ( I cannot see any reason why they would remove and swop the sensors during a tyre change)

[qprdude]

Aha!
Being a bit on the warm side again today, I popped the A/c on "Lo" and turned the fan(s) up full blast.
Lovely and cold.

Oi! said swimbo, there's nothing coming out of my vents. MMmm certainly nothing from the main middle vent that I could feel.
Could this be the fan fault? The vents on my side of the car are blowing cold, but to be honest, I think I remember them blowing a bit harder.
Are there two fans on these. Is it one for each side. Would this be a cause of non starting. So many questions.
On a brighter not, a quick scan of the warranty book suggests that somecooling stuff may be covered, but as I don't know what is on the car, it's hard to tell.


Covered, cooling system:- Radiator, oil pump, water pump, thermostat and viscous fan.

Covered, electrical system:- Thermostatically controlled fan motor, Heater motor.

[Hell Razor5543]

If they follow the same basic design as earlier C5s, there are a pair of flap motors (one per side) that move the flaps depending on what temperatures are required. These pivot between the hot, ambient and cold (a/c) air inputs. On the early C5 these failed because the shaft was not long enough, so the motor would become disconnected from the flap. I wonder if your warranty will cover this (as it may be a dash out job)?

[qprdude]

I thought the later models had a modified shaft
Doubt very much if it is under warranty. Hope it's not too expensive. Has to be done.

[qprdude]

Oh poo. I fired off an email to West Heath garage explaining about the passenger side blowers not working. Did you ever get that feeling as soon as you hit "send", that you should have checked to make sure .
I did.
I found that the passenger side was set to blow at the footwell vent only. SWIMBO was under the impression that switching the A/C on with the highest fan setting would direct the cold air to all vents! Oh dear, I have some explaining to do when the garage gets back to me.
Still, I can pick their brains over the starting problem after I have apologised about the fan.

[Hell Razor5543]

Oops!

[Stickyfinger]

So, is it SWIMBO who needs an "adjustment" ?.........hehehe

[qprdude]

So, is it SWIMBO who needs an "adjustment" ?.........hehehe

SSSHHHHHhh

[daviemck2006]

So, is it SWIMBO who needs an "adjustment" ?.........hehehe

Do you need a garage for that Rick [emoji48] [emoji23]

[qprdude]

I'm saying nothing guys. This is a public forum, and I need to be fed and cared for!

[Stickyfinger]

So, is it SWIMBO who needs an "adjustment" ?.........hehehe

Do you need a garage for that Rick [emoji48] [emoji23]

Is she ODB2 compliant, might need her fault codes deleting