Trouble with DPF filter and having some questions

[Nissp]

Hello!

I have recently gotten in some trouble with my Avensis 2008 diesel. I am by no means car person and need help with some questions that I have regarding my car.

To give some background information, the first sign of it came while driving on the highway and turning on cruise control ( will be relevant later). Maybe a minute after turning CC on the car it suddenly started losing power and CC was turned off. Motor varning sign as well as TRC off and VSC lighted up. The car lost power, as in couldn't accelerate properly and in slight upward slopes it lost speed and RPM went down even when going on lower gears.

I went to the workshop and got the error message P2002 and the car underwent a cleaning program which was supposed to forcefully clean the DPF. The warning signs disappeared, until about an hour later. This time I again turned CC on, and a minute later or so the car went poof and suddenly I was losing power again.

The obvious solution is of course to change the DPF, but I am wondering:

1.Why did the errors both times occured shortly after turning on CC. Was it just a coincidence?

2. Why is TRC off and VSC lights on? ( They turned off when the car was running fine after the cleaning.)

3. Is there some other part that can be the reason for failure? I heard someone talking about a sensor governing the oxygen/fuel resulting in clogging the filter, is there any truth in that?

4. The change in power was instantaneous, why is that? Is the power output regulated by some internal computer which restricts  it (limp mode?) or is it simply that the filter is clogged?

Hope the questions make sense, as I said I am not that well versed in cars.

//Nissp

[Heidfirst]

Hi Nils, welcome to TOC ☺️

Do you know which engine you have in your car (size, power output etc.)? Manual or auto transmission? If you open the bonnet does it say D-4D or D-CAT (D in green) on the engine cover? 

The TRC/VSC & engine master warning light can be brought on by various things. Modern common-rail turbodiesles (especially with emission controls like DPF) are really quite complex & everything is computer-controlled so yes, it can drop into limp mode to protect itself if it detects something not right.

[Nissp]

Hi and thank you, Heidfirst.

 

It says D-4D on the engine cover. It's 2.0L and 126HK.

[Guest]

I'll let one of the far more experienced people on here go into detail and correct me where im wrong.

But given your error code, and assuming its a competent garage, It sounds like your DPF might be the issue, and as a result, the various sensors in the system, such as exhaust, are telling the car there is a critical fault, and its going into limp mode.

I have had a near identical & repeating issue in a previous Mercedes C class. 
For a week prior I had had terrible fuel economy. Then the DPF failed on me one day, the exhaust sensors had a fit, and I lost most power since I was now in Limp mode, (AKA "you shouldn't really be driving it" mode). The Dash warning lights lit up like a Christmas tree everywhere. Limp mode then proactively shut down access to a ton of normal systems like Cruise control, traction, manual shift mode, etc, etc. Limp mode very really meant "limp" - it was sluggish as hell to drive.  Mercedes instructed not to drive it any further and it it got towed to the dealer where it was formally diagnosed as the DPF.

For me, the DPF failure was caused by a literal lack of driving, or more specifically not driving the car long enough to get the DPF hot enough to ever activate. (I would only take it out for a short drive each time - This is the biggest flaw with DPF's as an idea). Mercedes tried to Clean out the DPF, but it only lasted a month before it happened again. Second time Mercedes managed to get it right, and the car didn't have the issue again, plus I also made sure it got a good enough run each time.  Unfortunately for cars that only get used for short runs(Diesel only ones obviously), DPF problems are supposedly common.

Its still very possibly something else, but given the code and the garage's attempt to clean out the DPF, id say its your primary suspect.

Here is the "OBDII Trouble code Technical description" of your error if it helps, and it does answer your 2,3, and 4 questions. For 1(CC) , I can only assume it somehow triggers  the fault and check in its operation. Either that or its a co-incidence :)

P2002 = Diesel Particulate Filter Efficiency Below Threshold
Symptoms of a P2002 DTC may include:
-A drop in fuel economy occurs as the engine management system attempts to increase the temperature of the exhaust to burn off the excess soot in the DPF
-The check engine light will be on with the code "P2002." The light may stay on or light intermittently as the DPF regenerates. the engine will be sluggish on acceleration.
-The engine oil will exhibit dilution from the ECUs attempts to increase engine temperature. Some vehicles advance the fuel injection timing slightly after top center to afterburn a small amount of fuel to increase exhaust temperatures. Some of this fuel enters the crankcase. When the ECU determines the necessity to regenerate the DPF, the service life of the oil be shortened significantly
-if the DPF is not cleared the ECU will revert to the "Limp Home Mode" until the situation is corrected 

The causes for this DTC may include:
-Too much slow speed operation will cause this code. It takes heat in the 500c to 600c range to burn off the soot in the DPF. Even with the ECUs efforts in engine management, it has difficulty in creating enough heat to clear the DPF at slow engine speeds
-An air leak forward of the DPF will change the sensor readings resulting in the code
-Defective ECU strategies or components will prevent proper regeneration
-Fuel with a large percentage of sulfur will clog the DPF quickly
-Some aftermarket accessories and performance modifications
-Dirty air cleaner element
-Damaged DPF

 

[Heidfirst]

1 hour ago, Nissp said:

Hi and thank you, Heidfirst.

 

It says D-4D on the engine cover. It's 2.0L and 126HK.

interesting - the chances are that if that was in the UK it almost certainly wouldn't have a DPF but whatever country you are in the local specification may have been different.

[Nissp]

Thanks for the insight Simon.

 

I live in Norway, maybe that is something that should have been included, Scott. Why is it that D-4D isn't using DPF in UK? Is the NOx emissions already at a acceptable level?

[Heidfirst]

3 hours ago, Nissp said:

Scott. Why is it that D-4D isn't using DPF in UK? Is the NOx emissions already at a acceptable level?

They weren't required at the time. The D-CAT version (with a DPNR/DPF) of the 2.0 was available at 1 point to order but they sold so few that Toyota GB dropped the option. DPF with the 2.0 D4D didn't become standard fit in the UK Avensis until 2011.

[yossarian247]

I think at that point Norway had more stringent exhaust emission limits than EU countries. I know at that time for example some VW diesels sold in Norway were fitted with DPFs whereas the the same model sold in the UK was not.