Saved myself £120 with two minutes DIY

[NY]

My car (a turbo diesel) has a long history of "Depolution Failure" error messages with various symptoms ranging from dramatic loss of power (limp-home mode) to total engine failure (*). It's been in the garage for various fixes, most of them expensive (new DPF and cat; new pouch of "addiitive" which sounds similar to AdBlue; new glow plugs and a sensor).

So when it failed again, only about 2 months after the last fix, I thought I was in for another expensive fix. preceded by a £120 charge even to run any diagnostics.

The car was usable but very under-powered - getting up slight hills was a major exercise at about 20 mph :-(

I booked the car into the garage, then something made me check under the bonnet. Lo and behold, the turbo hose had come off :-( It took about 2 minutes (one of which was finding a screwdriver) to loosen the Jubilee clip, refit the hose and tight the clip. Normal service has been resumed - the car can actually go faster the 50 mph again and can climb hills.

So my poor car was running as a normally-aspirated (non-turbo) diesel, with any changes that the engine management system may have made to cater for this situation.

The warning light is still on, but I wonder whether it latches on until it's manually reset by a garage. Hopefully the garage will reset the light for a nominal charge. I wonder whether the work they did on the car 2 months ago involved removing/refitting the turbo hose.

(*) The total dying of the engine happened in the weeks leading up to moving house, when I was making journeys over to the new temporary house (my parents' holiday cottage) with cardboard boxes - wonderful timing. Each time it happened after I'd driven about a mile from home after starting from cold. I got used to restarting the engine, driving about 20 yards before the engine died again, repeat about five times and then the engine stayed on and the car ran perfectly for the next few days.

[Andrew]

Since the garage left that jubilee clip loose, I should go back and insist that they reset the service light at their expense.

[Bill]

In message , NY writes

The way forward is to seek out your own best diagnostics for whatever make of car it is. For my Jeep, I had already paid something like a fiver for the OBD2 bluetooth sender for a previous vehicle, Someone was offering free Jeep software, which was absolutely brilliant, allowing resetting of codes as well as diagnostics. For the Landie, I sent a few pounds to China ( half of which was refunded when I complained about the dry joints and the virus on the software CD) and bought a BMW kit that works with my laptop.

I had to take the first to the people repairing the Jeep, which diagnosed that they had shorted out some wiring while reseating the injectors, the second reset the Landie height system after the garage re-attached a height sensor that had fallen off.

Both garages had expensive diagnostics kit, but neither of theirs achieved a satisfactory result.

[NY]

I think I probably will do. Assuming that the work they did last time would have necessitated the removal of the hose, then it looks as if they are the culprit.

I was intrigued when they did the last work that they said there would be a large labour bill even to *check* the state of the glowplugs. Firstly, I'd have thought that the state of them (open/short/intermittent circuit) would be reported in the ECU. Secondly, I'd have thought it would be a quick job to disconnect and unscrew each plug to check it with a multimeter and to check that it wasn't coked up. As it happens, I did need new plugs (the first in 170,000 miles) so the increase in labour to fit new plugs was negligible. The garage made it sound like a major job, when it should be almost as easy as changing the sparking plugs on a petrol car, I'd have thought. I presume diesels (even HDi) still have one plug per cylinder, in the cylinder head, rather than a single plug in some common area which *may* be less accessible (though it shouldn't be if the car is designed to be maintainable).

I'm still not sure when made me check under the bonnet. I remembered later that I'd had a similar symptom when the hose had come off after another garage had serviced the car: in that case it happened within a few miles of the garage so I turned round, limped back and the guy came out and tightened it a bit further. Maybe subconsciously I remembered that time and it made me check. I can understand the hose coming loose: the first time I tightened the clip, I hadn't pushed the hose right the way along so the clip tightened against fresh air. But a skilled engineer would know to look out for that situation.

It shows how much a car depends on a turbo, though I imagine the ECU deliberately cripples the engine (to avoid an over-rich mixture with too little air) so it's probably worse on a car that is designed to have a turbo (which is not working) than on one that is designed to be normally-aspirated.

[Chris Bartram]

fault recurring.

[Brian Reay]

You can buy an OBD reader for most cars for

[Cursitor Doom]

I can see a new industry arising pretty soon if this increasing complexity keeps up. Rewiring the entire vehicle so the main VMU and peripheral modules can be removed and disposed of without adversely affecting the functionality of the car. New car owners wouldn't probably go down this route, fearing for their warranties, but for the second hand market, old-school car owners and technophobes it could be the best thing ever.

[Cursitor Doom]

IME if the underlying fault isn't fixed, the light will just come back on again.

[Brian Gaff]

Maybe but they of course would deny they had left it loose and in fact this is debatable.Worth a try though. If you have a nice young lady who could go back and suggest this, that has been known to work quite well by a friend of mine. Strange how although sexism is supposed to be frowned upon, it still has its uses.

Brian

[Bill]

[Huge]

*applause* I have queried this in the past and had it removed from bills.

[Dave Plowman (News)]

Not quite sure how a 'technophobe' is going to be able to do that sort of job. So you'd end up paying a vast sum to someone capable of such a thing. To save the small sum buying diagnostic kit of your own costs.

Sounds similar to converting a word processor to a typewriter. For those who can't be bothered learning how to use one.

[The Other Mike]

You massively underestimate how things are connected these days. Say for instance the simple act of switching on the headlights, replacing it with 'something simpler' might easily require a new column stalk as the existing one only speaks canbus , then new discrete wiring, a new fusing arrangement, and rather than the vehicle body module that processes the canbus messages you'll need something to actually switch the headlamp, and as the existing dashboard requires a canbus message to show the main beam indication maybe a new dashboard.

The existing wiring loom was almost certainly one of the first things fitted to the car post paint, so everything is built around it and there is not much spare room, so figure on a full strip out and a new wiring loom. Mass produced you might get it for 500 quid but it could easily be many times more.

For one simple function you've added a few kg to the vehicle weight and lightened your pocket by a few thousand quid. Now add on the cost of ensuring say the column stalk is compliant for crash testing and you can add a few 10's of thousands amortised over the sales of your headlamp switching replacement kit.

Now expand that 'simplification' across all the vehicle lighting functionality, and the heating and ventilation and across a range of manufacturers with hundreds of variations of specification.

Now do it for the engine controls and keep them compliant with the emissions requirements.

Or you simply go down the scrapyard and buy one of the replacement bits off the shelf for a few quid.

If the problem really is too difficult to fix then the vehicle becomes a scrapyard donor.