Hi all.This is my first post on here so I hope I’m in the right section.i am a mechanic for a local commercial garage.I would be grateful of some advice.A couple of weeks ago I had a 2009 daf lf 55 250 in with an emission warning on dash.i plugged it in with our Texa diagnostics and had fault codes 2772 and 2773.i flushed all lines and injector out with warm water they were blocked but faults still there so replaced nox sensor but still no luck.we then had it plugged in at local daf agent and they said module/pump faulty so replaced that.they cleared all faults and light went out now a week later light is back on with same codes.i also flushed tank and replaced with fresh adblue.Some help required please.i also have a merc axor 1843 with an emission warning to do tomorrow if anyone has any advice on common problems.Thanks in advance of any help.
Remove the fillter on the chassis see if you can see any blockage the check the pick up pipes should have a small fillter on the end some time when they put the system to gether they don’t take the labels off and it dissolves in the ad blue tank
Dont know about the daf but the merc is probably the diffuser valve blocked.(not always)
At rear top of engine you will see a valve with a test connector on top.Remove the test union and bend the air feed out the way…Unscrew small plastic filter from the valve,(small flat bladed driver gets it) and chuck it in the bin.Next a kettle of boiling water into the valve.Reconnect the air pipe with test union.Fire up the motor and red line it for a couple of seconds.Flashing managment light will go to solid amber(stored fault now not current fault)
Need DAS to put out lamp on MR ecu
Hi guys.Thanks for the replys You have posted.The merc was changed till today so hopefully it will be blocked diffuser valve like you suggested.The daf lf is still causing me a headache so anymore help is appreciated.
Thanks for the advice on merc axor Bking it was blocked diffuser valve like you advised.Flushed with hot water and was able to clear faults with Texa diagnostics so all good now.But lf is still causing problems.Thinking about it being possible blocked or contaminated exhaust cat.any other suggestions.
Corker:
Thanks for the advice on merc axor Bking it was blocked diffuser valve like you advised.Flushed with hot water and was able to clear faults with Texa diagnostics so all good now.But lf is still causing problems.Thinking about it being possible blocked or contaminated exhaust cat.any other suggestions.
Whats the fault code on the dash diagnostic?
Have you tried changing the fuel metering valve on the high pressure fuel pump, the control valve on the fuel rail, crank sensor and the ambient air temperature sensor in the wing mirror. I have changed these and cured various problems as if one is out the ad-blue will not dose correctly and can then cause problems. The solenoid on the fuel pump doesn’t generally show up on diagnostics (I have a Delphi) but I changed it on all of my vehicles, (5 LF’s and 1 CF) usually after I had all the others changed and this cured to problem.
I have found that with LF’s sometimes the faults it shows are where a sensor starts giving readings out of the set parameters and doesn’t mean it is faulty. I found this out the expensive way but changing each sensor as the diagnostics showed it was faulty and sometimes changing them twice.
I hope this helps.
Hi Bking.The fault codes showing up on Texa diagnostics are 2772 and 2773.
I guess you never got the DAVIE codes from the dealer ■■..There are 2 specific fault codes ,with a fault tree to follow, and it may just be that the ecu needs an update ,I suggest you go back to the dealer and get them to check the ecu software for the engine is up to date …As that is the first item DAF suggest you check and update
J Brickell:
Have you tried changing the fuel metering valve on the high pressure fuel pump, the control valve on the fuel rail, crank sensor and the ambient air temperature sensor in the wing mirror. I have changed these and cured various problems as if one is out the ad-blue will not dose correctly and can then cause problems.
…and the ambient air temperature sensor in the wing mirror.
Is this the same sensor that provides the outside temperature on the dash? Mine is reading a balmy 36 c. Didn’t think it was an issue but can anyone tell me if the ecu uses that same reading for dosing either fuel or adblue or anything else? If so sounds like I should get it sorted.
Recently had a rusty exhaust down pipe split which I got sorted pretty quickly but not before the engine warning and emission warning light came on. A few restarts and the engine warning cancelled itself but the emission one stayed on for all of the next shift.
Was worried it would go limp before long so got it booked in to get it switched off and hey presto it went out when I set off to get it sorted. Result! However, in the meantime been reading multiple threads on ad blue issues ready for the (inevitable) next time that light comes on. Seems another common problem is a filter getting blocked. Where exactly is that filter? It might be the first thing I check next time.
It is a Daf LF 55.220 Euro4
Th eambient on the LF is not an issue unlike it’s bigger brothers CF and XF,I d get it sorted anyway …The reason your MIL light stayed on was it due to being a NOX fault when your pipe split .Even DAVIE cant clear the fault because of the type of fault…DAVIE can programme it out .Though the correct way to extinguish the lamp it to drive it loaded up a gradient there is a fair bit involved ref temps etc .But over the period you have driven it you have met the criteria etc and that has put the lamp out itself
That is good news, thanks for that. Did a fair bit of motorway and fully loaded so yeah I s’pose that has done the trick. Will keep an eye on it. I understand the temp has to be something like 200c and the engine puts out most NOX when working hardest.
Be good to get the temp right on the dash too.
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the temp sensor will take 2mins to fit ,…most people cut and join the wires behind the mirror ,as if you try and fit it how it is supplied you will be hours