Just a mystery ( C4 Pic. 1,6 e-Hdi 2011 )

[rmunns]

This car never ceases to give. 8 months of abject misery with a serious (£1500-worth) fault displayed on the screen, but driving OK. Just the occasional very very slight misfire . I have got to the stage of consulting a lawyer against the garage that sold me the car, but that has all stopped now due to the virus. Anyway, while the car has been parked up (using other car) the battery flattened. Fitted new battery (what a job!) and found incredibly that battery I took out was the original, dated Oct 2010! That was on Monday. On turning on ignition, the 'Moteur probleme' message came up, exactly as before, with 'SERVICE' illuminated. But today, first time since Monday, no message, no 'peep'. And there is more. The ECO now works, it didn't when I got the car and it hasn't since, until today. So what is all this - a dream? Or should I not be inclined to say 'whoopee' too soon?

[Hell Razor5543]

The C series Citroens are very sensitive where it comes to their electronics. A weak battery can cause all sorts of weird problems. Having a new battery fitted probably has resolved the issues. What could be a good idea is to do a full BSi reset, just to make sure there are no glitches (if there are actual problems they will remain).

[rmunns]

Thanks, I have the details how to do a BSI reset, so I'll do it. But my main concern is that the 'engine fault' seems to have disappeared.

[GiveMeABreak]

Hi roger. 10 years for a battery on one of those is stretching it a bit far - especially as you have Stop Start. The Stop Start only functions when a host of parameters and conditions are met - one of which is the battery in sufficient condition / charge. Although it has an energy storage capacitor for the Stop Start, all the conditions have to be met for it to function.

So this may well help with the electrical glitches, just the mechanical faults to deal with now...

[rmunns]

Marc............... thanks again for your help and encouragement. But the huge mystery is that the SERVICE light and the 'moteur default' (engine problem)) message have GONE. I agree about the battery - well over 9 years is a lot. The ECO has never worked since I bought it - in fact I didn't even know what it meant ('if all else fails read the instructions').

I need to now get a diagnostic done to see if the mechanical 'faults' are still there.

[Hell Razor5543]

Consider the possibility that (because the battery was weak) some systems were not 'waking up' properly, and so were not ready to respond to the 'Are you awake?' query from the main ECU. This could then cause that ECU to 'believe' that the 'sleeping' ECUs were at fault, and threw up an error state. Because there is now a new battery all of the ECUs are 'waking up' properly, and so (when they receive the 'Are you awake?" query) respond correctly. The main ECU can now 'see' that all of the electronics are responding properly, so does not need to bring your attention to any faults (as they no longer exist).

However, doing a diagnostics check should, at least, bring peace of mind.

[moizeau]

I'd be inclined to agree with James here. If the warnings have gone out on there own, the relevant parameters have been met and the car has decided there is no fault anymore.