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[Viral_Jim]

Evening all,

Question for those with soot chucker knowledge. Was driving back from North Yorkshire today at a steady 75, 160 miles into a 175mile journey the Evoque when it threw a Restricted Performance error. While nursing it home, it also threw up a gearbox error and the autobox locked itself in neutral. Did a restart and the gearbox error cleared, but restricted performance persisted. However, once the codes were read and cleared, the car behaved like nothing had ever happened 

I borrowed a friend's iCarsoft and read the codes. Got a P244A - Differential DPF pressure too low and a soot concentration (inferred) of 7.74g/m3. Engine oil level is at the full mark but not over full. Usage pattern is genuinely mixed, a number of short journeys, but always one run of >50 miles every 2 weeks or so. Also, I recently replaced both 12v batteries, so I doubt there's any issue with voltage drop throwing random errors.

My primary suspect is the DPF differential pressure sensor, but I'd be keen to hear if I'm missing something obvious!

[Doctor Gollum]

What's the engine speed at that cruise?

I wonder if it wants to do a regen but the exhaust is too cold and whether dropping it down a couple of gears would solve the problem.

Deliberately bought a diesel without a DPF just to avoid such issues.

[STEMO]

Don't know about your RR, Jim, but my Astra does a regen every 280-320 miles. There's no way I'd getaway with one 50+ miles every two weeks (or so).
You don't say how many miles you do between these longer trips.

[Sir Tigger KC]

Evoque? What are you doing in such a girly thing Jimmy?     

I thought you drove a big butch Disco 5! 

[Viral_Jim]

I thought you drove a big butch Disco 5! 

I do, but we wanted to split the driving and I don't share my toys 

You don't say how many miles you do between these longer trips.

Tbh it's probably somewhere between 100-150 miles of short runs as a max. And even then, they aren't all really short, it's frequently in the 20miles ish range, so I'd hope it would cope ok...

What's the engine speed at that cruise?

I wonder if it wants to do a regen but the exhaust is too cold and whether dropping it down a couple of gears would solve the problem.

Could be DG. Engine speed is only about 2000 rpm. I will have a mess with the diagnostic and see if it will show the last regen. Tbh though I don't think the DPF is blocked as the error is differential pressure too low. I would have expected a blockage to give the Differential pressure too high error. IE high pressure on the engine side, low pressure on the atmosphere side as the exhaust gas can't pass quickly enough through the DPF.

A pressure too low error is what I'd expect if you gutted the DPF and the gas could pass through it with reduced resistance...

[TheBoy]

I'd be inclined to drive it in such a way to ensure it does complete a regen, then check the (inferred) DPF contents.

The usage pattern could be enough to be problematic for DPF cars.  Its trivially easy to get the DPF light on without the car moving

[Marks DTM Calib]

Check the pipe to the pressure sensor, quite common for them to fail on any DPF equipped car from any manufacture (used to patch the Zaf one up every 12 months)

That would align to the fault code 

[Sir Tigger KC]

I'd be inclined to drive it in such a way to ensure it does complete a regen, then check the (inferred) DPF contents.

The usage pattern could be enough to be problematic for DPF cars.  Its trivially easy to get the DPF light on without the car moving

An Italian tune up? 

[TheBoy]

I'd be inclined to drive it in such a way to ensure it does complete a regen, then check the (inferred) DPF contents.

The usage pattern could be enough to be problematic for DPF cars.  Its trivially easy to get the DPF light on without the car moving

An Italian tune up? 

For a decent distance, not letting revs drop below about 2500rpm.

[Marks DTM Calib]

Its reporting a low differential pressure, not a high, so its not a clogged or clogging DPF 

[TheBoy]

Good point, well presented.

Still, I'd still give it a bloody good ragging, because, well, err, hmmm....     ...thats what I do

[countrywoman]

I second that, a good ragging never did any harm----------

[TheBoy]

I second that, a good ragging never did any harm----------

Its my standard fix for everything

even when its not broken

[YZ250]

I second that, a good ragging never did any harm----------

Its my standard fix for everything

even when its not broken

You say that but sometimes it works.    When I had my new F33 430 bmw auto (the one TB said I looked cool in  ) I was just about to overtake when a message popped up saying ‘Transmission Malfunction’ and limp mode prevented the car getting past 50mph. I pulled over and a restart cured it, but the next day it did it again. On the third time it did it I was doing duel carriageway speed but approaching a roundabout. In temper I slammed it rapidly down the gears using the flappy paddles, until the screaming engine and gearbox dragged it to a halt. I had that car a further ten months and it never faulted again in my ownership. 

[TheBoy]

I second that, a good ragging never did any harm----------

Its my standard fix for everything

even when its not broken

You say that but sometimes it works.    When I had my new F33 430 bmw auto (the one TB said I looked cool in  ) I was just about to overtake when a message popped up saying ‘Transmission Malfunction’ and limp mode prevented the car getting past 50mph. I pulled over and a restart cured it, but the next day it did it again. On the third time it did it I was doing duel carriageway speed but approaching a roundabout. In temper I slammed it rapidly down the gears using the flappy paddles, until the screaming engine and gearbox dragged it to a halt. I had that car a further ten months and it never faulted again in my ownership. 

It fixes everything.  One way or the other.

Kill or Cure