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DPF light stayed on after forced regen


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Honda accord 2009
Honda accord 2009 2.2

Hi all, hope some can help make sense of these cryptic cars!

DPF light came on and car went into limp mode, took it to garage and they said no fault codes and it wouldn’t regenerate. Took it to Honda who checked and said AC compressor had gone, bought compressor and garage fitted it and it went through a full regen this time, however light and limp mode still active. AC is also working fine.

As they were closing up they said bring it back after weekend if it still on and limping.

In the meantime I decided to reboot the ECU via the fuse, this cleared the light and limp mode.

My question is, should I have needed to do that? Is this just going to come back again?
What is a full regen?
I thought you had to drive it hard for 50 miles (long time for example) to clear it out.
Did it on the wifes nissan note a while back, recommended to take for a long hard drive every so often.
Anyway I don't think regens last for long and it will soon be troublesome again on these accords.
I meant forced regen, so they connect up a computer and regen while stationary, this is necessary when the light with the exclamation mark comes on the dashboard. You can’t drive it to regen when this light is on.
Yep, it’s going to come back. Once you start needing even one forced regen, it’s time to solve it properly. Drop me a line if you need help.
So even though Honda diagnosed a faulty AC which has now been repaired, there could be another issue? Could they not have diagnosed that at the same time?

I’m also guessing that the light will come back on when it needs to regen again?
The AC is only required for a forced regen, not for normal regeneration during a regular driving cycle. I’m just speaking from years of experience with these cars, once you’ve needed just one forced regen, the time is up for that dpf.
So are you saying new DPF? I’m guessing it would need to be a genuine replacement? Or are there other options? I can’t have it removed as it’s required for the MOT.
You'd be looking @£1500 for one from honda, probably more than the car is worth, then fitting if you are not able.
Some on ebay for £400-500 I'd be going for, don't know if anyone on here has fitted cheaper dpfs?
You can have it removed and it will still pass an mot apparently.
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Avoid aftermarket, they’re cheap for a reason and will just add to your problems.
Well I need to make a decision really, my journeys are not really suited to a diesal so really I want to trade it in for a petrol.

Feels like options are:

- Genuine replacement (expensive)
- Aftermarket replacement (will this even buy any time?)
- Clean?

Feel like I just want to trade this in while the light is off if possible.

What's the deal with removal? This isn't legal anymore right?
Trade it in and buy a petrol if you’re not doing the miles mate.
DPF light is back on after 700 miles, interestingly this is the second time in a row it's come on during high revs (4500+).

I'm seriously considering removal now, but what are the chances of getting caught, failing MOTs etc.?
Avoid a further regen, you’re causing untold damage to your turbo every time you do one.
My local mechanic does removals, and I've been ***ured that there will be no issues with the NOT.
MOT + DPF is an interesting topic that i've been trying to get my head around myself (for no particular reason other than personal curiosity)

Since 2013 it's been mandatory to check for the presence of a DPF (if the vehicle had one from factory) but as it's just a visual check in reality it's easy to pass with no DPF as long as it's not obviously been removed. There is a mention of a "smoke opacity test" but it doesn't look like this any relevance as a test for whether a DPF is present or not. You're probably more likely to fail that for a bad tune or a faulty car.

There have been rumblings about greater enforcement of DPFs - the most recent information directly from the DVLA that I can find is this article which mentions that they desire to implement "PN testing" where the DPF is actually tested for functionality, which would mean anyone without a DPF would fail.
There is a line in the above "likely to be post 2013 diesel engine vehicles" - which means that most, if not all Accords will likely be exempt anyway - that's probably a relief for some
It’s an easy choice for me, bin the DPF for £300 or pay 2.5k to replace it. If it fails an MOT in the future I’ll just bin it or sell it off cheap.

Good to hear they may not enforce this check on older diesels though, the garage I spoke to said a lot of people remove them, particularly from transits and they’ve never had to fail one.
Forced regens don't usually work and most dpf issues can be resolved unless it's damaged. There's a YouTuber mobile mechanic called O' Reily's that got me out of trouble with one of my vehicles, might be worth giving him a call or in my case watch a few videos, bought some product and diagnostics box and worked it out. Might be worth buying some aerosol dpf cleaner and squirting it down the right pipe for a tenner or so and check your oil level.

There's some good info in the comments on below video, a cheap replacement pressure sensor and something about a service bulletin first few years of the iDTEC engine that updated the ECU to reduce or prevent oil dilution. Should have been applied if the car was dealer serviced. That's if you want to go down this route...

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Hi all,

I'm waiting for my DPF to be removed, I'm still using the car for short journeys in limp mode, but in all seriousness how many miles would I be able to do in this state before doing damage? It was supposed to be removed yesterday but it's been delayed and I'm anxious about whether I should stop driving completely.

You absolutely should not be driving it in this state, and hopefully wherever you’re taking it actually has experience with these cars. I’ve had to solve many bodges over the years.
I'm thinking in terms of if there is an emergency and I need to use the car for a short trip, I understand this will clog the DPF up further, just curious to know how clogged the DPF is when limp mode comes on and how much driving it will take to kill the car completely.
Hi Mantorok,

I'm in the same boat as you.
My dpf clogged back in January, had to get a forced regen at my local dealer.
Foward to now, driving along the motorway and the bloody light comes on again. back to the main dealer only to be told that the dpf filter is toast (they couldn't force a regen)

I know Fahad is the man to sort it but he lives so far from me it's not an option.
So I've managed to find someone local to remove and remap it.
Though like you, i need to use the car in the meantime. and also concerned if this could cause more damadge whilst in limp mode.

Yes I too would've used Fahad but 350 miles is a little far.


I'm using a company called DPF Doctor, I originally contacted when the red light came on a few months ago, he immediately suggested that due to the mileage and the situation that removing was the best option, he seemed knowledable, asked exactly which Accord model and rattled off what would be required to remove etc. They claim to have done around 200 with no recurring issues.

Until that first MOT goes through I'll be nervous, but I've spoken to the garage as they are in my village and they said they've never had to fail one with the DPF removed.
It’s really not for me to comment guys, and I certainly am not in a position to offer any comfort around other people’s work. If you’re confident you’re getting a proper job then you take your chances. Best of luck.