C5 Tyre pressure sensors

[Bob1954]

MOT testers will know there's an issue because you get a warning light/message on the dash. Any warning will be an automatic fail, Renaults are indeed wheel specific.

Yep, sorry I meant that they cannot test the system in reality to ensure it has not been disabled, and doubt if they will be allowed to test it.
Daft thought.... If you have a puncture on MOT day on the way to the testing station and fit the spare, the alarm registers, so that is still a fail? Stupid really....
As an advisory system it is a good idea, in practice I have found it unreliable, so it got binned....

[miked]

I haven't got first hand experience of this but if the air is escaping out through the valve stem the I have heard that the valve core, i.e. the bit that holds the air back is the standard schrader design and can be removed and replaced with one from a non-sensor equipped valve with something like this tool: http://www.sjscycles.co.uk/weldtite-sch ... prod19402/" onclick="window.open(this.href);return false;
Of course, if the leak is between the valve body and the rim then this doesn't help.

[Lynnzer]

I was on the way to my nephew's garage to use his Lexia equivalent to turn off the sensors but they appear to be voided already. Pressing the check button goes through the motions and just shows a dash against eadch wheel instead of an OK,
So I didn't go and just went home instead.
I've had a couple of messages since then on my various travels that tells me the front offside wheel pressure isn't being monitored, and the service light is shining on the dash. Apart from that all's OK.
So, it's my contention that no MOT tester would know about the non operable sensor since the message doesn't come on and stay on.
I'll leave things as they are for now and maybe consider turning the sensor off when I get another issue to deal with. That's liable to be the reversing sensors as my wife screwed one up when she reversed at speed into a lamp-post. I've had it put back when the bumper was repaired but it still shows as a faulty sensor. Maybe these have to be reset too when they have suffered a problem?????

[fosseym]

Just an update - bought 4 decent wheels with excellent tyres off ebay for £42 quid. And no sensors !
Will report back on the error messages when I fit them.
Does anyone have a Lexia in the Cornwall area ?

[Trainman]

Lexia Locations are here: http://www.frenchcarforum.co.uk/forum/v ... 19&t=26807" onclick="window.open(this.href);return false;

[markflip]

The MOT is currently in a bit of a pickle tbh, the new legislation isn't passed yet so there's an extended, extended 'warn but don't fail' guideline until Parliament get their Act (pun intended) together. From a road safety point of view, it makes sense not to allow a car out from what is intended as a safety check, with a safety based item indicating a fault and i think pressure sensors are a good idea in principle (I'm sure we've all checked our tyres to find them seriously below what they should be at some point) although Citroen's design leaves a lot to be desired and they are far from alone in this!! When the new MOT legislation is eventually passed, turning off the pressure sensors with Lexia or similar will allow the vehicle to pass an MOT, as the envisaged new test only covers warning light sequence anomalies for safety specific systems (engine management, ABS, EPS, SRS, tyre pressure etc) when fitted. If no initial tyre pressure warning light comes on with ignition, an MOT tester has to assume it's not fitted and they can't strip down your wheels or deflate the tyres to check, the MOT remains a 'look-see' inspection only. That said, if you do use run-flats, I can't stress enough the absolute need for type pressure sensors, over 50mph for any distance and they are at serious risk of catching fire if punctured - even 'normal' tyres don't "look flat" until well below 20psi as a rule, but handling can be seriously compromised by the time they have reached this pressure, which is why I say they are a good idea in principle. Weekly checks are a really good idea regardless, but if you pick up a nail/screw on the start of long journey on the first day, a pressure sensor will tell you well before you re-check them or notice from a 'walk by' visual inspection.

[Bob1954]

Agreed that in principle these sensors are a good idea, and will give early indication other than a massive blowout, but there are practical problems.
Certainly in Citroen's deployment, presumably also with others, the wheel is tied to one particular location.
The classic of switching wheels to even out tyre wear would require reprogramming to ensure the system continues to function, a expensive addition.
A puncture requires deployment of the spare, but this intitiates an alarm also. if this happens on the way to a MOT, you could be failed despite having a safe and serviceable car, stupidly in my view.

Admitedly this does not apply to the UK, but there are also legal/insurance requirements to use winter tyres elsewhere in Europe.
So do you fit different wheels and tyres and put up with the alarms, or switch tyres and re-seal the sensor (assuming some kludge tyre fitter is not let loose on it and busts the sensor).

I simply got the sensors deactivated, and reverted to old technology, checking tyres manually.

[Trainman]

Certainly in Citroen's deployment, presumably also with others, the wheel is tied to one particular location. The classic of switching wheels to even out tyre wear would require reprogramming to ensure the system continues to function, a expensive addition.

Not necessarily true, If the C5 is the same as the C6, then the wheels can be moved around the vehicle, in fact, you can actually have 5 wheel programmed to the car.

[Lynnzer]

That's the way my C5 works. Doesn't matter where the wheels are. Except in the boot of course.
As to the warning of non operational sensors, I'm driving for around 5 to 10 minutes before I get a notification that the front offside wheel isn't being monitored.
That#'s exactly what it says. Front offside wheel not monitored. That's more a statement of fact rather than something a MOT tester could point to as a fault. The fact is, I have replaced the sensor with a normal valve. I'm OK with getting this message and keep monitoring the other 3 wheels than just switching the whole thing off. As the replaced valve is a legal valve there's no reason at all to suspect it could be a reason for failure of a MOT test. It just simply isn't monitored.

[fosseym]

So I put the new wheels on without the sensors - drove for a few hours with no messages at all, then got a message saying four sensors missing. Same message comes up occasionally - I can live with that considering the full set of wheels and tyres cost 42 quid plus 20 quid balancing !!!!

[vborovic]

When I've bought my car, 2nd hand, the specification stated that it had tyre pressure monitoring installed. I thought, great (cool, if nothing else). After driving it, it seems the tyres (rims to be more precise) don't have pressure sensors installed. I've almost decided to buy 4 sensors and have them installed, but I've backed up from that, due to several reasons.

When you're driving, it is almost impossible to not notice you have a flat tyre (especially at higher speeds). The tyre sensors are calibrated at certain pressure (not sure which, default should be 2,4 bar at all four if I remember correctly), and they should go off when the pressure drops from the calibrated zone (I'd say below 2,2 bar), which would mean you would have to pump the tyres ASAP, to avoid the constant notices ... in practice, people don't do that, they drive for months on 2,0-2,2 bar pressure ... with nothing significant happening. If you have micro leaks in the tyre or the rim edges, you would have to repump more often (because the sensors would urge you to do that), risking damaging the valves. But now, the valve isn't a cheap 5€ rubber, but a 100€ (or more, new item) micro machine ... Which can be damaged with every tyre change on the rim. In the case youu have summer/winter tyres and rims, to just switch when the other season comes, that would mean a trip to the Citroen Service to have the system preprogrammed to either monitor (or not) the pressure valves. Each visit means less € in your wallet. If the valve package would be 100€ in total that would be a different story, but with 400€ for 4 valves, and the servicing that costs extra, no thank you.

[JohnD]

The tyre sensors are calibrated at certain pressure .

The tyre sensors quickly learn whatever pressure has been put into them - and that becomes the calibrated pressure. My rear wheels were inflated to 3 bar because the car had been heavily loaded. Last week I got new tyres fitted on the rear wheels. Ten minutes after leaving the depot I heard the gong and saw the warning - "Both rear wheels punctured". I knew what was wrong so continued home. The tyres looked OK but when I attached the pump, the reading was only 1.9 bar. More pressure removed the warning notices.

I use a breakers alloy wheel, complete with a sensor as a spare wheel. Whenever it's fitted on the car, after five minutes running, I get a warning message telling me the tyre pressures are not being monitored. If wheels are removed and replaced in a different location, the system is confused. But only until the next start up.

[vborovic]

Heavily loaded for tyres to be at 3 bar ... what did you load, a Citroen C1? ... ... I must admit I didn't know about the self-adjusting part of them, but the thing is they're still not that smart (human logic, if you will) to really know if the pressure in the tyre is right or wrong, or when to activate themselves, due to different car uses and other circumstances, as you yourself have mentioned.

[Stickyfinger]

My rear wheels were inflated to 3 bar because the car had been heavily loaded.

3 BAR ?? Wow !....I use mine for Cast Iron Radiators and have never gone that high..... why ?

[JohnD]

3 BAR ?? have never gone that high..... why ?

The car was fully loaded with the caravan on the hook. Also the door sticker gives 3 bar on the rears.