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check engine light with P2002 code

13K views 24 replies 5 participants last post by  phantom 
#1 ·
hello.

for a few months now, due to home office, i have been driving my giulietta (2.0 JTDm 170PS @191'000km) 1-2 times a week, with mostly 50-80 km/h speed. lately, i have the feeling that, sometimes, it is jerking a little bit while accelerating. the clutch has been replaced a couple of years back about 25K kms ago, and it does not happen all the time, so, i am guessing, it is not the clutch slipping. and once in a while, i feel there is power loss.

it has been parked under a few trees, and i have not washed it for a long while. it is covered in pollen and such, so, i am suspecting, there might be some problem with air filter or the fuel itself. i finally got around to wash it, after 10-15 minute motorway drive. on the way back on the same highway back, the 'check engine' light came on, with power loss. i can drive it around sometimes now, but it mostly feels like in limp mode. i could not get over 40 km/h at 3rd gear on a hill, which was really sad, since a bit of light hill climbing is one of the most fun parts of driving it :)

i checked with a simple obd2 scanner, and read the error code P2002, which apparently means Diesel Particulate Filter Efficiency Below Threshold B1. so, maybe a sensor fault, or dpf regeneration failure. funnily enough, the 'check engine' light came on while on highway, during which it could do some regen.

since it does not have much power and i cannot dare to push the engine, i cannot drive it happily to get dpf regeneration going. i have already booked with the mechanic next week, but does it make sense to clear the error code, if 'torque lite' allows that, and check if i can drive around with some power for a dpf regen? or, is it safer to wait for the garage to get a juicy bill?
 
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#2 ·
The DPF needs to get very hot to burn off the spot deposits; a few minutes at highway speed won’t be enough. You need to give it at least 30 minutes at speed - engine speed is more important than road speed. Try driving in a lower gear to keep the revs up
Failing that there may be an air leak before the DPF that will mess up the sensor readings. But first, before looking for faults, I’d go with the simple option that the car has done many short trips without getting properly hot and has partially blocked the DPF.

Edited to add - as you’ve already tried driving you could try running the engine at a faster idle, say 1500rpm, while stationary. It might take a few minutes but may improve it though to allow a highway run afterwards.
 
#3 ·
The explanation for that code is slightly different from my list. it means the dpf is overfilled (2nd level).

If all works as it should, an active regen only requires 10 minutes to complete after starting. Passive regens need more time and power, and just like an active regen needs a working catalyst. The catalyst stores NO and converts it to NO2, and it's the NO2 that gets recombined with soot or fuel in the soot filter to burn it clean and release co2 h20 and N. Passive regens require about 350C, active regens at least 550C. Passive regens take longer.

My guess is the car tried to regen but couldn't get the dpf temp up. This can be due to overloading as the fault code suggests (not enough exhaust flow to get the sensor hot) or the sensor itself was covered in soot insulating it from heat, or the sensor or wiring is damaged.

If your driving isn't suitable for regular active regenerations, you could add a fuel borne catalyst to the tank, these reduce the temps at which regens start by about 100C, at least for active regens. peugeots and citroens add this to every tank of fuel automatically. Eolys it's called and you need about 20 ml to a full tank. Has a distinct smell and I've come across one otc fuel additive that has the same colour and smell, from mitsubishi. MZ320180 part number, or you can buy eolys from any peugeot citroen dealer in 1 liter bottles for about 50 pounds. With that stuff in the fuel I've been able to go 3000 miles between regens.

Something to consider if the garage cant find a fault with the temp sensors.
 
#4 ·
Had a further look and P2002 is a pressure issue at heart. The dpf is considered clogged because of too high pressure differential. Alfa says to replace the dpf, but I'd have a go with washing it if an inspaction doesn't reveal damage. Then consider how this happened, as it's not from missing 1 regen...
 
#6 ·
take the code reader with you, some cars allow codes to be cleared while driving.

On these engines, it is reported the EGR valve closes after 22 minutes of run time, so if that is true the NO in the exhaust will go up and the chances of a succesful passive regeneration aswell. EGR is closed when active regen starts anyway and turbo pressure is kept as low as possible. Get DNA in D and watch the turbo pressure to judge if regen is active. Another way is watching momentary fuel consumption.
 
#7 ·
tried to clean the code after warming up the engine, but it came back right away. so, i drove around for 15 minutes at higher rpms, and then parked and cleared the code. it did not come back right away after starting the car. but let's see when i try later after a drive around.

though, it is so frustrating to almost floor the gas pedal, yet reach around 50 km/h at 2nd gear at 2500 rpm on almost flat road. unless there is a descent, 3rd gear won't reach over 50 km/h either.
 
#10 ·
so, today, i dropped the car at the garage. they called me to tell that the dpf seems to be clogged up to 75%, and they did a forced regeneration at the garage. unfortunately, it apparenly did not fix it, within the time they ran it. they said, it came down to 57%. so, they suggested me to drive it around on a highway for a long while to see if that helps. i will try that over the weekend.

but the main problem is, even after cleaning the error, it comes back within minutes, and the engine drops to limp mode. i wonder if i can get to highway speeds at all. is there a fuel additive that might be of help, without damaging something?

replacing with original part will possibly cost more than the current value. would it be ok to replace it with this product, which costs cheaper? it says euro5, so, i guess it is legally fine.
 
#12 ·
i did ask particularly whether the sensors were alright. he said they were ok, but, i do have a feeling that they hardly checked anything. i guess, they simply saw the error code, and ran the tester for 1 hour or so. it seems like they are always overbooked. maybe, there are fewer mechanics available due to the pandemic situation.
 
#13 ·
its fairly easy to check the pressure sensor. Engine off, no pressure difference. With the engine on, the pressure goes up with engine load.

The way you describe the massive power loss I think there's a real blockage, it's certainly running slower than normal limp mode. Blockages eat engine power.

I Would get some Eolys, add 60 ml to the fuel tank at first and 20 ml for every next tank. 1 bottle costing around 50 euro (100 swiss franks?) will last for 48 tanks of fuel... If that cant get the blockage out it likely isn't soot and will need physical removal. the eolys can be got from peugeot/citroen dealers, or probably from car supply stores but the pricing will be similar. Eolys powerflex is the latest version, part nr 9736A0 at the dealers
 
#14 ·
thank you. i appreciate your time and answers. it does help a lot to hear from the experienced before talking to a mechanic :)

i will try eolys later as well. today, i went on a highway ride, trying to stay in higher rpms. unfortunately, 4th gear felt too much for >90 km/h for long, so, did most of it on in 5th gear, around 2000 rpm at 80-120 km/h speed for about 1,5 hours. since, soon after i clean the error (can do that only when engine off), it quickly comes back putting the engine in limp mode, i barely could accelerate over 90 in slightest ascent on the road. actually, the error comes back even when i clear it and wait stationary in idle for a while. unfotunately, at the end, i still have the error.

what i have experienced before this thing came up, and also experienced during today's ride, is the jerky/stuttery vibration of the car at times. i think, especially when the gas pedal is barely in the first few cms, it feels as if the car is quickly surging ahead or the opposite, like misfiring, skipping a beat or something. the rpm needle stays the same though. so, i either have to press the pedal more, or drop the pedal. sometimes, pressing the pedal more does not help. there is no 'misfire' fault code, though. fault with throttle pedal or sensor? am i right to think that it is not the clutch slipping, because it is usually at low throttle?

and sometimes, in idle, especially when engine is cold, the needle drops, and then engine reacts to recover. does this point to a dirty fuel, fuel filter, air filter or injector? (due to seldom driving and seldom filling up)
 
#16 ·
hmm...
by the way, this driving on the highway is not for nothing, right: if the exhaust temperatures are high enough, the passive dpf regeneration will happen anyways. can i do something myself to initiate active regeneration with the fault code active:

If the filter develops too much pressure then the last type of regeneration must be used - a forced regeneration. This can be accomplished in two ways. The Vehicle operator can initiate the regeneration via a dashboard mounted switch. Various signal interlocks, such as park brake applied, transmission in neutral, engine coolant temperature, and an absence of engine related fault codes are required (vary by OEM and application) for this process to initiate. When the soot accumulation reaches a level that is potentially damaging to the engine or the exhaust system, the solution involves a garage using a computer program to run a regeneration of the DPF manually.
 
#17 ·
No you probably can't, not without the proper software anyway. They do this to prevent the engine to regenerate continuously in case of an error, which drives up fuel consumption by 0.5l per 10 minutes, causes excessive fuel dilution of the engine oil and is in the end a fire hazard.

If you can't get where you need to be while regenerating or driving, remove the dpf and try cleaning it with water. if that doesn't work or it's obviously damaged inside replace it. the vegaz will do if the fitment is good enough.
 
#18 ·
well, i added some particulate filter cleaner to the fuel, and went on highway runs with high rpms. first couple of runs, the error came back, but on the last one it did not come back. it is good to get some power back to the engine. thanks for the recommendation, i could not get the same brand but this one has good reviews as well.

though, i went on one more ride on the highway, this time trying the dynamic mode. it was well at the beginning, but after a while, another 'check engine' error lit, so, i pulled over to a gas station to check the error. this time, it said P0238 - Turbocharger/Supercharger Boost Sensor A Circuit High, which might apparently be a sensor or wiring issue. i cleared the error, and drove back fine without it lighting up again, well, making sure not to request too much power from the engine. I hope it does not come back again :)

meanwhile, i want to also give a fuel system cleaner additive a try, maybe it will help with the stutter i feel from the engine. but should i wait until i use up the tank with the particulate filter cleaner first?
 
#19 ·
yes, circuit high means an electrical fault. No need to wait for the particulate filter cleaner, you can mix it. The stutter could be the reason your particulate filter clogged. Something must be wrong anyway as particulate filters don't just get clogged and the stutter isn't normal either
 
#20 ·
the sensor error did not come back when i drove today over the highway, but i did not really push the rpms or use dynamic mode. though, when you accelerate, there is a lot of dark smoke coming out of exhaust nowadays. i guess that is expected with the clogged filter and all.

this stuttering thing feels weird, so, i dropped by the mechanic today. normally, in idle, you could feel the engine almost stalling, and then raising the rpms to recover. though, when the mechanic was checking, it ran all normal :) i could not convince the mechanic to check the fuel system, he insisted that all is due to the clogged dpf showing the black smoke as evidence, and he recommended me to drive on the highway hoping that will clear it up until there is an error code.
 
#23 ·
Thanks, Eloise.

Unfortunately, it did not work out that well yet:
  • garage did static regeneration, but did not clean up
  • used STP Diesel Particulate Filter Cleaner: after cleaning the error code, it works for a couple of days, then the error comes back
  • used STP Complete Fuel System Cleaner along with STP Diesel Particulate Filter Cleaner: similar result, error comes back after a while
  • used STP Diesel Injector Cleaner: I have to admit this impressed me. Within 15 kms or so, the power suddenly came back to the engine, even though the error comes back after a while. Injectors might have finally breathed after a while :)
  • So, last Sunday, I cleaned the error code, and took the car on a highway ride. With more power available, I was enjoying a nice ride, until after 1 hour or so. Then, I realized pressing the gas pedal was not doing anything, and I was losing speed. So, I parked at the side of the road. The engine was running, but barely up to 2500 RPM with floored gas. I cleaned up the P2002 code again, and I tried to continue on the slow streets, but very soon the error came back with a 'Insufficient Oil Pressure, Stop Engine' warning, and the engine stalled. Luckily, I was able to brake and park on the side of the road.
  • The engine could still run, but, with very low RPMs and danger of stalling, I did not dare to continue the road back to home. I called the Road Assistance to bring the car to the garage.

I will ask the garage to do some checks:
  • replace air filter
  • check and clean MAF sensor
  • replace fuel filter
  • check and clean/replace EGR valve
  • maybe do other service tasks (@193000 kms, the owner's manual does not list the tasks :))

Let's see if these will help. Otherwise, I will have to get DPF cleaning service, or get DPF replaced.
 
#24 ·
first action from the garage: we found a leaking tube between egr and throttle, which costs 250 CHF (~210 GBP)
does that make sense? which hose are they talking about?
i hope it is not the constant humidity in the front left side of the engine that has been there forever?
 
#25 ·
so, they said that they replaced the cracked hose (some air intake hose, but not still sure what exactly it is), and they were able to do the dpf re-generation this time. the car has the power back again. i even did a tour of a few alpine passes to celebrate, in 'dynamic' mode :)
 
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