Isuzu DEF regen problem

Isuzu DEF regen problem

Posted in the Isuzu NPR Forum

Jeff

Robertsdale, AL

#1 Sep 5, 2013
Every few weeks I have to put my NPR back in the shop because the engine reduce power light comes on. The regen required red light comes on first, but only for a couple of seconds, then the check engine and engine reduce power light comes on.
Jay

Florence, MA

#2 Mar 22, 2014
Jeff,

It's obvious that you need to do manual regen done. There is a switch you need to press and it will take between 20 to 30 minutes while in park.

You are likely not telling the whole story. The system must have given messages in the dash with green regen needed. Watch some youtube videos on isuzu npr emissions and regen.

Your driving is likely short or city which will plug up the DPF more. Sustained highway driving of atleast 30 minutes would
bogie

Hockessin, DE

#3 Nov 25, 2014
Got a 2012 Isuzu def light flashing and loss of power
Nathan

Richmond, TX

#4 Feb 11, 2015
Jay wrote:
Jeff,
It's obvious that you need to do manual regen done. There is a switch you need to press and it will take between 20 to 30 minutes while in park.
You are likely not telling the whole story. The system must have given messages in the dash with green regen needed. Watch some youtube videos on isuzu npr emissions and regen.
Your driving is likely short or city which will plug up the DPF more. Sustained highway driving of atleast 30 minutes would
False. I have the same problem. I do mostly long hauls, no messages, only use she'll diesel, and I have done manual regens. They keep using the you must have bought bad fuel excuse.
Miami

Brooklyn, NY

#5 Jul 2, 2015
Nathan wrote:
<quoted text>
False. I have the same problem. I do mostly long hauls, no messages, only use she'll diesel, and I have done manual regens. They keep using the you must have bought bad fuel excuse.
I am writing from a 2014 Isuzu NPR, on New Jersey Turnpike. Just drove to NYC from Miami, and now, on a way back - no power.

Last time it happened arround DC. This is the second time.

Extra days for crew, plus hotel, while waiting for part.

You can imagine how it makes me feel about Isuzu, and it's reputation as a reliable business tool.

Did I mention that the truck box is completely empty, in case someone wondered.

I wish we took the old one for this trip.
D Guilford

Dunedin, New Zealand

#6 Jul 15, 2015
Check to make sure that your service people are using the correct oil. Vehicles with a DPF require a low ash oil else the oil will actually accelerate the blocking of a DPF filter.
Murphy

Castroville, TX

#7 Feb 17, 2016
I have a brand new 2016 isuzu NQR crew cab . It has less than 5000 miles on it . Today I was driving at 65 miles per hour in cruise control when suddenly the cruise control shut off and the display showed a red "exh. system" light came on . It has been regularly regenerating without any problems and has plenty of DEF fluid . The truck had to towed to the dealer . Very disappointing . I wonder what they will say . This is my service truck so without it I can't make a living .
Busy Mike

Jackson, TN

#8 Mar 24, 2016
I have a 2012 npr diesel, numerous trips back to dealer over re gen issues, we have went completely by the book, used the recommend motor oil, def fluid, the whole nine yards! We use the truck for lawn applications. Was told by my dealer today that the truck was basically not designed for these applications because of the long idle times. The truck has a PTO which drives the pump. Now I'm told ,by my dealer, I need to switch to a gas burner. The truck has only 50.000 miles and Isuzu can't seem to overcome the emission problems. I have had an incredible amount of down time and talked to other lawn applicators with the same issues. I bought the truck because of the PTO. Now, they basically don't care to resolve the issue, want me to buy a gas burner and buy an auxiliary motor and pay to have the spray chassis changed. I truly thought Isuzu was a reputable company. The truck has also had rain pour through the driver door since day one on a brand new truck. Anyone else experiencing similar issues?
Mark Melbourne Australia

Melbourne, Australia

#9 May 29, 2016
Was considdering an ISUZU 87-190 TIPPER...NOT NOW THOUGH.. I value my money and my time.
Imperial concrete

Castle Hill, Australia

#10 Jun 22, 2016
I have 2 npr250 models and no problems at all. In fact im just about to buy an frr600 pto for a line pump
jbanxy

Alexandria, Australia

#11 Jun 23, 2016
Jeff wrote:
Every few weeks I have to put my NPR back in the shop because the engine reduce power light comes on. The regen required red light comes on first, but only for a couple of seconds, then the check engine and engine reduce power light comes on.
hi you need to get the system cleaned out it sounds like its has a blockage like on our npr 300 which just clocked over 500,000 klm did exactly what you said ours used to go thru an auto deign every100-150 klm on the road we drive ours to canberra from syd and back daily,it has got so bad it is now 95% blocked and has cost us a packet to get cleaned we get it back tomorrow so will let you know how it went,we have a fleet of nlr npr nqrs
cheers justin
Phil

North Tonawanda, NY

#12 Aug 8, 2016
I have a 2011 Isuzu npr hd after having the regen filter cleaned it still regens after 50 miles. Watching the bars it takes 27 miles for the first bar, 18 miles for the second bar, 1 mile for the next two bars, 3 miles for the fifth bar and then regens after another 3 miles. Could the sensor be shot?
TIM922000

Houston, TX

#13 Oct 8, 2016
Murphy wrote:
I have a brand new 2016 isuzu NQR crew cab . It has less than 5000 miles on it . Today I was driving at 65 miles per hour in cruise control when suddenly the cruise control shut off and the display showed a red "exh. system" light came on . It has been regularly regenerating without any problems and has plenty of DEF fluid . The truck had to towed to the dealer . Very disappointing . I wonder what they will say . This is my service truck so without it I can't make a living .
I'm having the same problem. 2016 NPR 4,600 miles. It's been the shop 4 times for a bad knock sensor. I did a manual re-gen with no result. the dealer told me that they were going to get some big wig from Isuzu to check it now. Good luck!
DCop

Albuquerque, NM

#14 Oct 25, 2016
I own a 2012 NPR. It has been in the shop 7 times in last 16 months and it all relates to emissions system. Now it is there because the DPF canister is cracked and they are trying to figure out the "root" cause for its failure.
Kris

United States

#15 Nov 16, 2016
Phil wrote:
I have a 2011 Isuzu npr hd after having the regen filter cleaned it still regens after 50 miles. Watching the bars it takes 27 miles for the first bar, 18 miles for the second bar, 1 mile for the next two bars, 3 miles for the fifth bar and then regens after another 3 miles. Could the sensor be shot?
Excessive regen normally caused by lack of air or to much fuel, which in turn either is causing a rich condition causing excessive soot to build. I.e. Dripping or leaking injectors. With that said, this condition can be induced by improper repairs that have been done. If injectors or a injector been repalced without replacing the injector fuel line and retorquing in proper sequence can allow fuel to leak into the crankcase and cause an over full condition. Fuel lines are one time use only. The excess oil/fuel mix is sucked into the pcv system from vacuum produced by the inlet side of the turbo. Set through the intercooler and then into the intake manifold and then to the cylinders. With the excess and the injector doing its job there is to much fuel in the cylinder to be burnt, causing a rich condition or soot. This can also cause detonation not necessarily heard, damaging the swirl chamber in to of the piston. Particulate filter and converter need to be cleaned every 100k miles or 3300 engine hours. Differential pressure sensor tubes also need to be replaced because they build up soot inside skewing the sensor reading. Boost actual and desired pressures need to track each other, dirty diffuser screen in front of the maf sensor or bad maf sensor will cause this also. Really needs to be checked by a Isuzu dealer with a technician with complete knowledge on how the system works. They are tricky and diagnosis will take some time because each trucks usage is different. Good luck
ClassicTent

Howell, MI

#16 Dec 18, 2016
I see tons of problems.. lots of frustration without any real solutions. If anyone fixed theirs please post it up.
So I Bought a 2012 NRR with 80,000 miles.. here I sit at 83000 miles/ in power down mode.. without the option to push it into manual regen. I maintained the vehicle by the book (it was new to me) so I went through the works as I wanted to keep this for 10+ years.. Cleaning the filter seems like a short term solution. Has anyone thought of hollowing/drilling out their filter?
Off to the dealership to get bent over..
Murphy

United States

#17 Dec 18, 2016
TIM922000 wrote:
<quoted text>

I'm having the same problem. 2016 NPR 4,600 miles. It's been the shop 4 times for a bad knock sensor. I did a manual re-gen with no result. the dealer told me that they were going to get some big wig from Isuzu to check it now. Good luck!
After the red exhaust system light came on and it was towed to the dealer they checked it all out and said no problem found . Not too long later I got a recall letter to bring the truck in and they changed the parameters on the regenerating system computer . No problems till around 29,000 miles then I started getting the check engine and down power lights to come on . I would clear them with a handheld dcanner but it did not get better . When i took it in for the 30,000 mile service they determined that my fuel filters were clogged and reducing the fuel pressure and it wasn't allowing the regenerating to complete . My filters have supposedly been changed every 10,000 miles . I now have about 32,000 miles and everything seems to be ok for now . For the most part I am very happy with truck and it stays loaded and fully stocked for our service company . My nqr weighs about 16,000 lbs. I may start changing my 2 fuel filters at 5,000 miles and the dealer can change them every 10,000 . That way they will be changed at least every 10,000 in case the dealer 'forgets' to change it . Its not real easy to change as mine is a crew cab . I am also considering a BG fuel system cleaner . I average almost 700 miles a week . I also have the extra fuel tank so I have a 63 gallon capacity . I have now had the truck on the road for about a year and other than the 2 or 3 times with the regenerating system it has performed very well and has been a big step up from our previous stepvan service truck .
Victor

Houston, TX

#18 Tuesday Dec 20
I bought used nrr with 100k miles. ive put less then 300 miles on it and have paid over 6k is shop bills from this def system...never had any regens light needed come on. the truck simply lost power and the dash lit up like a christmas tree, I really think we need to get together and class act sue isuzu for this. Everyone that i talked to that owns a isuzu with the def system has had problems with them. So in my mind this is a manufacturer malfunction!!!

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