Power steering failure

[Natasha_Young]

I’ve also tried jumpstarting it from another car after it’s been sat overnight (this is when the power steering will definitely not be working) and that doesn’t get the power steering back either. (The car always starts fine even without jump starting). But the same thing happens, I sit and rev, engine off and on, power steering back.

[myglaren]

I suspect a failing battery despite the test, which may have been too brief and with a battery with too low a capacity.
See if you can borrow a beefier battery to try out - a known good one if not a new one.
Replacing the alternator can be expensive, especially if it isn't at fault.

[Natasha_Young]

Perhaps this might be a stupid question and apologies if it is- but wouldn't the jump start rule out a battery problem?

[myglaren]

You would think so but if your battery has a failing cell it could upset that arrangement.

Man I worked with had lots of similar problems with his Megane C+C until the bad cell was detected.
If possible, check each cell with an hydrometer - not possible with maintenance free batteries unfortunately.

[Natasha_Young]

Don't think that's possible with mine sadly. Do you think the alternator could be the alternative problem? Or does it not sound like that kind of issue? Car engine always starts fine, it's just the power steering which fails at first start up.

[myglaren]

I couldn't say with any certainty but the battery should be capable of powering the power steering on it's own, for a while at least, as Marc has observed in his C5 when the alternator belt snapped.

I haven't had a car with electric power steering until the current one so have no experience with these systems unfortunately.

[Natasha_Young]

So is this pointing to a new steering rack or ECU problem? I've been into so many garages and no one can seem to work out what's wrong and I don't want to chuck money at something if it's not going to fix it.

[GiveMeABreak]

Ok, the trouble is this issue can be several things.

If you have a Stop Start system with reversible alternator, it has been known that there can be problems with the LIN network internal to the alternator which can cause the network and communication issues. Second, there are specific tests that Citroen would run as there are known Technical Service Bulletins for the power Steering faults on the DS3, including one of these fault codes (U1121). But this requires fault finding and testing, so it is hard to say here on a Forum, as we obviously cannot undertake the tests.

Whatever you decide, it will require some specialist electrical testing by someone who knows what to do - so it may be better to bite the bullet and get Citroen to diagnose it for you / check if any TSBs apply in this case. Depending on the results of the tests, it involve a repair to the connections, or a replacement power steering unit Natasha.

[Natasha_Young]

Update: Mechanic has found that the alternator isn't charging, but the alternator itself is working fine when tested outside of the car. Any ideas? (I don't have a stop/start system). Still waiting for Citroen to get back to me about the issue/to book the car in but I've been told there are no software updates needed for the car.

[Hell Razor5543]

This is going to sound silly, but when the ignition is turned on (nut the engine has not been started) is there a battery symbol light that is lit? If there is not, that could explain the problem.

[Natasha_Young]

Yeah, the battery light is on at that point then goes off after the car starts.

[Hell Razor5543]

OK. The reason I asked is that the light bulb can make up part of the 'exciter' circuit, and a blown bulb can prevent the alternator from initiating the charging (I have seen that happen).

[Natasha_Young]

I see, thanks. I’ve just had a call back from Citroen and have booked it in for tomorrow. The nearest dealership is an hour away which isn’t so great. Will update with the outcome/diagnostic results incase this thread can help anyone else in the future.

[Natasha_Young]

Update: According to Citroen it needs a new steering rack and new alternator (although the alternator has been bench tested elsewhere and works fine...)

[Natasha_Young]

Steering rack alone = £1400 plus £300 labour. Citroen will only cover £250 even though there is a known issue with the steering rack.
Off it goes to the scrap yard!