Isuzu D-max 2015 DPF

[NDNDNDND]

We have a 2015 Isuzu D-max 2.5t that's used by my wife for farming. As such it gets a lot of short, shunting journeys of less than a mile. It's hard to avoid, it's the nature of farming, however the vehicle does get used for the occasional longer run - usually a couple of journeys exceeding 20 miles every fortnight. We've owned the vehicle for about 18 months, it has about 120,000 miles on it.

Last night, while driving down the motorway, I think the truck started a DPF regen - it felt rough and the engine sounded more clattery, as it has done before when performing a DPF regen. After five minutes or so, it sounded a bleep and the DPF warning light started flashing, followed shortly after by the CEL and (bizarrely) the TCS warning light.

Car has thrown a code P242F. I can't find many comments referring to D-Maxes in particular, but the generic code seems to imply the DPF is buggered and needs to be replaced.

Can anyone suggest any advice? Is DPF cleaner in the fuel worth a try? Will using premium diesel instead of Tesco make a difference? LS swap?

Many thanks,

ND

[stevieturbo]

First thing would be to check readings to see what sort of pressure difference there is across the DPF.

Then clear the codes and see what happens. Possibly do a forced re-gen on a proper long drive.

Really, when a car is doing these re-gens it should alert the driver of it stating how it needs to be driven for it to try and be succesful.
Often when it happens, people think something is wrong and slow down, which is the total opposite of what is needed.

Or yes, LS Swap.

[NDNDNDND]

Thanks for the reply. The only diagnostic tools I have area cheap ELM327 copy and Torque Pro on my phone. I can read the DPF pressures with torque (although I've not tried it yet) but what would I be looking for?

The truck doesn't seem to have a regen button and I don't think it's possible to force a regen using Torque. Is there any other way or is this a trip to a friendly garage?

It's my wife's truck, so I don't drive it that often, however I think the little farty dfp symbol flashes when it's doing a regen. It's a very basic truck with no displays, so it doesn't give any instruction on how to drive. I kept my speed up and cruised in fifth instead of sixth, booting it occasionally when slowing for roundabouts and junctions.

[NoAlternator]

Since you or your wife are farmers, would you be willing to do something like take the DPF off and hose it out? It'll wash out a load of black soot then if you let it dry out should be OK for a bunch more time.

[NDNDNDND]

NoAlternator said:

Since you or your wife are farmers, would you be willing to do something like take the DPF off and hose it out? It'll wash out a load of black soot then if you let it dry out should be OK for a bunch more time.

I can't work out if you're joking!

Can you really do that?!

[stevieturbo]

NDNDNDND said:

Thanks for the reply. The only diagnostic tools I have area cheap ELM327 copy and Torque Pro on my phone. I can read the DPF pressures with torque (although I've not tried it yet) but what would I be looking for?

The truck doesn't seem to have a regen button and I don't think it's possible to force a regen using Torque. Is there any other way or is this a trip to a friendly garage?

It's my wife's truck, so I don't drive it that often, however I think the little farty dfp symbol flashes when it's doing a regen. It's a very basic truck with no displays, so it doesn't give any instruction on how to drive. I kept my speed up and cruised in fifth instead of sixth, booting it occasionally when slowing for roundabouts and junctions.

Proper tools will be needed to diagnose and rectify problems...I'd rarely trust basic generic OBD readers like Torque. For most part they are a novelty than a proper tool although they can be used with caution.

[NoAlternator]

NDNDNDND said:

I can't work out if you're joking!

Can you really do that?!

I am serious, but I'm also far from an expert. There's a lot of videos on youtube of people doing this, and they say they're still trucking.

[GreenV8S]

NDNDNDND said:

I can't work out if you're joking!

Can you really do that?!

I've never done it myself, but it does seem to be a thing. Usually done with a pressure washer rather than a hose pipe as far as I can see. I haven't seen any mention of the water blast damaging the face of the matrix, but it's something I'd look out for if I was trying this.

[NDNDNDND]

Thanks for the advice, I've spoken to a local garage who have recommended a dose of Cataclean and long motorway drive in a low gear as a first attempt to clear the DPF.

Failing that, they've suggested bringing it in for a forced regen.

Prior to that, would it be a good idea to take the truck out for a longish motorway drive in third or fourth gear, just to burn to some diesel and see if that'll get the exhaust hot enough to regen? How much of a risk would there be of simply increasing the amount of soot clogging the DPF?

I might use Torque to monitor before and after DPF pressures to see if there's a difference.

[Megaflow]

It’s worth a try, but the DPF might have just reached the end of its life.

When the DPF regenerates it converts the spot to ash. That ash stays in the DPF. The DPF will only take so many regens before the the ash load is just too much.

120k miles, lots of short journeys, it might just be full.

[NDNDNDND]

Ugh, I didn't realise ash simply accumulates until the DPF is full. How rubbish.

I'll attempt to burn it off on the motorway, failing that I'll adapt the exhaust to something more fit for purpose, perhaps a series of stub stacks poking out of the bonnet.

[stevieturbo]

NDNDNDND said:

Thanks for the advice, I've spoken to a local garage who have recommended a dose of Cataclean and long motorway drive in a low gear as a first attempt to clear the DPF.

Failing that, they've suggested bringing it in for a forced regen.

Prior to that, would it be a good idea to take the truck out for a longish motorway drive in third or fourth gear, just to burn to some diesel and see if that'll get the exhaust hot enough to regen? How much of a risk would there be of simply increasing the amount of soot clogging the DPF?

I might use Torque to monitor before and after DPF pressures to see if there's a difference.

A long motorway drive in first gear ? hit whoever said that a slap.

A simple long drive at 70mph may encourage and allow a re-gen attempt. But getting a garage to do the same and force a regen would probably make more sense than driving endlessly and hoping.

[stevemcs]

Forced regens produce a lot of heat, at least if you try and get it to regen while its driven allows the air to cool the car.

When was the oil last changed ?

[NDNDNDND]

stevieturbo said:

A long motorway drive in first gear ? hit whoever said that a slap.

A simple long drive at 70mph may encourage and allow a re-gen attempt. But getting a garage to do the same and force a regen would probably make more sense than driving endlessly and hoping.

Third or Fourth gear, not first! It was suggested to me to cruise at about 3,000rpm. That said, taking it to a garage and getting them to force a regen is looking like a good plan.

stevemcs said:

Forced regens produce a lot of heat, at least if you try and get it to regen while its driven allows the air to cool the car.

When was the oil last changed ?

We've had the truck about 18 months, but haven't even done 10,000 miles in it yet. I'd literally just bought all the filters to do a service on it. I'd have to dig out the previous history, but I believe the truck was serviced before we bought it.

Does anyone know how you can force a regen on an Isuzu truck? I can't find anything anywhere, not even a suggestion of what diagnostic equipment I would need.

[stevemcs]

You would need diagnostics to carry out a forced regen, however there is little point in doing that if there is something that stopping the car carrying out a regen. Services are based on time or distance, just because its only done 10,000 miles in 18 months doesn't mean it shouldn't have one. Also with some cars (mazdas) you have to reset the oil quality light and the service light otherwise they will not carry out a regen as they believe the oil quality is low.

I would start by changing the oil resetting the service light and go from there.

[NDNDNDND]

Truck passed its MOT on Saturday. I was advised by the garage that they'd had trouble with D-Maxes before, and that their diagnostic equipment was unable to force it to regen. I was sent back out to drive up and down the bypass until it had performed a regen on its own, which it didn't do.

After about half and hour doing 60mph in 4th gear, I simply went home, plugged in my cheapo ELM327 knock off OBD2 reader and cancelled the code. Full power was returned and the truck drove perfectly, passing it's MOT.

The problem is probably still waiting to rear its ugly head, so in the meantime we will only use premium, branded diesel from now on and hopefully a new lockdown won't emerge to prevent us from using the truck for a few slightly longer journeys.

I have read about an oil-dilution parameter, but I can't find any information anywhere on how you reset it, or if it really is present on these trucks.

I gave the truck an oil and filters service on Saturday. It travelled only 3,000 miles between its last two MOTs.