2021 MX13 pac car dpf and scr efficiency issues in need of egr tuneup

[mikkhh]

New sensor from dealership installed, with engine OFF sensor reading is fluctuating at 5-20 hPa. That does not seem logical or normal.

New sensor baseline where it fluctuates is 10hPa

Year old sensor baseline is 4hPa

Wiggling the wiring or plug does nothing, wiggling the ECM does nothing, keep in mind the truck is only five years old.

Those readings are relative, it means intake sensor reading - ambient pressure. IMAP readings with engine off must be 0. Engine running at idle should be 20-30hPa positive boost pressure.

[mikkhh]

One truck started complaining about nOx output value not changing when expected. Brand new original sensor from dealership installed, is showing sometimes -200ppm value, dealership claims this is normal. Keep in mind that aftertreatment system on MX13 is made by red engine manufacturer.

Starting to really doubt the origin of those genuine parts that dealership is selling...

[mikkhh]

Well the box says nOx sensor, generic cardboard box, no logos or anything. Only one sticker with logo and part code. Other no logo bigger sensor written with words exchange, dealership wants back old sensor.

Looks like dealer ripped off again, truck goes into limp mode when under load and output nOx stays negative after some time.

Keep in mind that this truck had been serviced and repaired at dealership mostly, but nOx sensor was Hella brand one. As far as I am aware of those sensors are made to order by Continental/Vitesco... I have only bad and worse experiences using Hella branded sensors on passenger cars, terrible chinese junk that has been dead on arrival or has failed shortly.

Looks like the parts dealer is selling are just some crappy chinese junk. Or maybe just really unlucky and fault percentage is that high on nOx sensors, IMAP sensors.

[mikkhh]

Oh well again DPF faults on second MX13

Diff pressure sensor is reading 14hPa with ignition on, engine off. That is BAD. Should read ZERO. New sensor will be ordered from Netherlands Paccar, have more trust in them than dealer.

Will pull whole exhaust to replace sensor AND clean pipes, to make sure that they are not blocked. Will order new dpf seals etc and try to clean SCR doser too then.

Will pull temperature sensors and test them using propane torch, to make sure they are not getting stuck.


Have attached photos why it is must to clean out pressure sensor tubes.

[mikkhh]

new sensor installed 4-6 hPa ignition on. On another truck shows zero, new sensor there shows zero. Have run the calibration. Have also tested with pressure gauge with sensor unplugged and only applying pressure to high side

After engine running some time and turned off sensor reads zero until I remove key and do ignition on after some minutes sensor reads 6hPa. Same with sensor from a working truck and also one from a wheel loader. Wiggling wires did not change anything

Will test another dpf/scr ecu from another truck, will try to plug it in and see if reading moves with ecu. If yes I will pull programming and swap those ecu s around and see what happens.

That aftertreatment ecu fault is common cause on dd13 15 for differential pressure issues.

[mikkhh]

Well I did swap around the aftertreatment control modules. Will see if fault code travels to another truck now... Also cleaned vent hole on both of them, now both trucks read 0-1hpa with engine off ignition on.

Most likely there is barometric sensor inside those modules and it self calibrates and takes that to account for calculating differential pressure?






I did also clean plugs properly, also took of cover of plug to check for any visibly damaged wires and to clean from all of that dirt and gravel. Did not see anything wrong