2011 LF55 Emissions MIL Lamp

UK PROFESSIONAL DRIVERS FORUMS OWNER AND FLEET OPERATORS FORUM (INTERACTIVE)
1

Hi, any advice greatly received.

I’ve got a 2011 LF55. The MIL lamp came on before Christmas. It seemed to come on just after washing it down for test.
My Delphi reads 3226-15 NOx sensor value too high (long term) active.

We had a Nox sensor in our stores so replaced it. Lamp still on and with MOT approaching sent it to our DAF dealers. According to invoice:
Connect to Davie investigate warnings. Found Nox sensor fault (long term). Re-programme ECU. Recheck - all faults cleared.

Picked vehicle up, all OK but then a few days later, lamp back on. Sent back to DAF. This time according to invoice:
Connect to DAVIE check fault and found air present at injector -OK. Run dosing tests and check quality of adblue - OK. Free off and remove rotten adblue injector returning nut. Clean injector (slight build up) crystallisation on tip. Clean threads on exhaust pipe. Refit injector with new nut. Reprogrammed engine ECU to extinguish warning lamp. Carry out road test. Ensure all plugs are dry for adblue system.

Picked vehicle up, all OK but then a few days later, lamp back on. Sent back to DAF. This time according to invoice:
Investigate emission warning light on. Connect to Davie found fault relating to CAT or mechanical failure of engine/inlet/exhaust as all other tests OK. Reprogramme ECU to extinguish light as requested.

It went for test the next day and the lamp stayed off. It passed the emissions also.

Lamp came back on after though. Still on now. Have replaced the exhaust with a reconditioned one and have also changed the wiring harness that goes to the Nox sensor and dosing unit. The old loom had a joiner missing and was full of dirt so thought we’d replace that as well.

I cannot extinguish lamp myself so not sure yet if the exhaust that I fitted yesterday was faulty or if we still have a problem. Does anyone know at what point will the MIL lamp go out on it’s own (if it does?)? Next tests I suppose would be compression tests? I’ve done pretty much everything else.

Oil and water are clean however the water level does drop occasionally. Cannot find a leak anywhere but exhaust smoke looks clean also.

There was a bit of smoke yesterday when starting up after fitting exhaust but it soon cleared, assumed it was just burning off. It’s been fine today.

The lamp was off last week for all of a day then came back on.

Now coming up with 3226-0 which is still Nox sensor but also limited power.

Thanks

2

This fault code is stored when emission of NOx measured by the NOx sensor (F791) exceeds the limit of 5 gr/kWhr.

This fault can result from several mechanical failures. Perform the job ‘Check/flush dosing module, EAS’ to determine a mechanical problem with the EAS dosing module.

The ECS-DC4 electronic control unit also activates the MIL the second time the diagnostics run and fail.

The reason it was re-programmed is DAVIE can not clear the fault,the vehicle does a self NOX monitoring and will extinguish the light when it sees everything ok

The causes are listed below

The MIL cannot be switched off and this fault code cannot be cleared with DAVIE. See ‘Procedures to switch off the MIL’.
AdBlue quality not within the specifications or liquid other than AdBlue present in the AdBlue tank
Too little delivery of AdBlue by dosing module EAS (B494).
AdBlue nozzle plugged (partly).
Mechanical failure of the engine, fuel system or intake/exhaust system

The flush is best done by fill the ad blue air filter with boiling water remove pipe from the nozzle run the engine and after about say 5 mins .I can’t remember the time it should blow the water out with the air ,if it doesn’t the pump unit is U/S …The reason it says NOX high is that the ad-blue side is not working ,the NOX sensor is just doing what it is meant to do

3

Hi Norb, thank you so much for replying.

OK, will look at the flush. I think I’ve eliminated pretty much everything else. It’s had the adblue Injector done and I’ve just done injectors as was on limit on smoke test. Oil level not going down and no smoke so don’t think rings or anything.

With the ad blue filter, how can you release the air before removing it?

The MIL lamp seems to come on after being either washed or going through a wheel wash. Is there any wiring faults too that could bring this on?

4

The lamp has been off for a couple of days now and done approx 200kms. If there was a fault present, would the MIL come straight back on again? I’m keeping the truck on clean work and away from water for a while, want to try that.

5

it is odd that it happens after a wash ,you can check the plugs wiring …There have been cases of people who jam probed in the plugs to check for voltage and spread the pins which causes faults …Have ypu drained the ad blue tank and checked the pick up filter in the tank

6

Hi Norb

Haven’t done much to the adblue side, had a air filter before Christmas when serviced it. Gauge goes down so assume its dosing OK and no fault codes to dosing or pump. Had a new wiring harness for the system as well.

I temporarily put an emulator on it to knock code off, then when it’s off I disconnect it to see what factors put it on again.

7

it doesn’t matter that the ad blue goes down it may be weak /contaminated and can’t lower the emissions …

8

OK, cheers. I’m going to keep it clean for the time being and see what happens. I’ll know withing a couple of days if it’s water related or not.

Thank you very much for your help, much appreciated.

Can you release the pressure from the adblue filter before removing it?

Cheers

9

Hi

So ad blue pick up filter all good. Filled new ad blue air filter with boiling water and after 15 mins of running I’m getting an occasional mist. Not sure what I should be getting.

10

Kebabkarlos:
Hi

So ad blue pick up filter all good. Filled new ad blue air filter with boiling water and after 15 mins of running I’m getting an occasional mist. Not sure what I should be getting.

You should be getting the hot water out ,flush it 3 times or as many times as you want ,but it it doesn’t clear the pump requires replacing

11

Hi Norb, many thanks for this. It is clearing, think it’s OK.

Can I just ask something?

When MIL came on local DAF reprogrammed ECU to knock light off. Went for MOT, passed, but emissions on limit. Changed injectors, one was over fueling a lot.

Sent back for smoke test at same place and emissions halved. Would it need to go back for DAVIE to reprogram after the injectors were changed?

Is the system trying to run at the old parameters and still putting the warning on?

Regards

Karl

12

No the injectors do not need programmed

Because you have a specific NOX fault DAVIE can not clear it ,the vehicle itself will clear the fault once it is happy that everything is ok …The dealer where being lazy and instead of repairing the fault and roadtesting it to confirm it was fixed …The programmed it out ,because DAVIE can’t clear it …There is nothing wrong with any parameters ,if the light comes on you still have a fault

13

Hi Norb, again, many thanks…

I only did the one flush, I will do a few more Monday. My mobile fitter who helps done dosing an air checks and said they were OK. But if I can’t get hot water from the Injector pipe would you say the pump is faulty?

The pump is literally the last thing to do. Before writing the engine off.

14

Kebabkarlos:
Hi Norb, again, many thanks…

I only did the one flush, I will do a few more Monday. My mobile fitter who helps done dosing an air checks and said they were OK. But if I can’t get hot water from the Injector pipe would you say the pump is faulty?

The pump is literally the last thing to do. Before writing the engine off.[/quote

If you pull the pipe of the nozzle on the exhaust pipe ,after roughly 2 minutes of the engine running on idle ,there should be air coming from the pipe…your engine will be fine

15

Thanks Norb, so if just air after 2 mins or so do you thing it wants a pump

16

correct

17

Hi Norb

Just to update, fitted a new dosing module and sent to DAF to have it reprogrammed. It’s now done just over 1500km and the MIL lamp has stayed off.

The truck has had a new SCR system pretty much, Nox sensor, loom, dosing module, exhaust.

Got an ABS lamp on and am reluctant to let DAF touch it after the ad blue fault.

Brake pressure limitation sensor short circuit to power supply
Brake pressure limitation sensor short circuit to earth or open cicuit

It’s also occasionally thinking the parking brake is off when it is not. You only really notice it if the door is open or your trying to engage PTO.
Is the parking brake switch in the lever itself or is it in the chassis going to the spring brake chambers.

18

MIL lamp just came on. Done 3500kms. Same fault code, Nox sensor value too high.

Would this come on if the adblue was low? I’ve got an inactive code from yesterday lunchtime, adblue tank level too low.

9am this morning Nox value too high. Could this be related as there’s nothing else on the truck to change.

19

MIL lamp coming on after 3000km(ish). Safe fault, Nox value too high.

Whole adblue system renewed. It’s had a catalyst, loom, nox sensor, dosing module. Nothing else to change.

Assuming its the engine now. I think we’re at the end of the road.