Engine light

[spkennyuk]

Definitely fits into the intermittent category as the light disappeared on its own this afternoon. Will put the Autel on again later and see what it is saying now.

Check the percentage full on the DPF. After you changed the battery did the light come on at start up or while you were driving ?

It could that the car triggered a DPF clean that has failed to complete. This usually happens if you finish your journey and turn the engine off before the regen completes or you get stuck in traffic mid regen which would drop the revs too low to complete the regen. The other option would be the PCM triggered a regen but could not complete because the DPF was too full. This can occur if a regen fails two or three times due to short journeys.

The PCM injects diesel into the DPF in order to burn off the soot which raised the temperature inside the DPF. If its getting too hot because it is clogged then you could see the P042800 code.

If the PCM doesnt see the same condition after two or three restarts then it will clear the fault unless it changes to permanent.

Educated guess at this point is that your DPF was fairly clogged say 70 to 90% full and on your journey today it has triggered a regen cleared some of the soot out and it is now operating within the correct temperature range and self cleared the code.

DPFs have improved since they first appeared mid 2000s. When a regen triggered then the car would become sluggish and the engine note would change by a significant level. You would also see sparkly burning soot particles in your rear view mirror if driving at night during a regen.

Modern cars its much more difficult to spot the signs while your driving. As a result its easier to not notice and turn the car off mid regen.

Check if the P042800 code has gone to historic status or gone altogether and check the DPF percentage of full. I suspect its probably at or below 70% now somewhere between 50 and 70% and now operating within the correct temperature range.

 

[PKM_999]

Does the Autel let me know the DPF% ? Never noticed that but wasn’t looking for it.

Both times the engine light has appeared have been after the wife has driven it a short distance to the supermarket. The first time it came on at start up the following morning and this time it came on while she was driving. She said she also heard a bang from under the car and that the alarm sounded 3 times after she parked up. (I presumed she hadn’t shut a door correctly and that some rubbish hit the under tray but did wonder if the alarm was due to a voltage drop)

 

[spkennyuk]

Does the Autel let me know the DPF% ? Never noticed that but wasn’t looking for it.

Both times the engine light has appeared have been after the wife has driven it a short distance to the supermarket. The first time it came on at start up the following morning and this time it came on while she was driving. She said she also heard a bang from under the car and that the alarm sounded 3 times after she parked up. (I presumed she hadn’t shut a door correctly and that some rubbish hit the under tray but did wonder if the alarm was due to a voltage drop)

Dont let the wife drive it problem solved !

Voltage drop would trigger the alarm. Having said that if a door wasnt latched properly then the car would normally fail to lock and bounce the locks actuators open again.

Which autel unit do you have ? If you have a section called exhaust system then the DPF soot level should be in there. You should be able to read the soot level and force a regen from there. It does depend on which Autel unit you have.

Normal soot level would be 25 to 45/50 % before the car would initiate a regen. After that it would keep trying each time the car was upto temperature but if these failed then it would continue to fill up with soot. 90% or above then depending on the car your likely to start seeing P2xxx codes requiring a forced regen.

Short journeys can cause all sorts of dpf issues. Most cars will trigger a regen every 150 ish miles the car travels but if you do 15 x 10 mile journeys for example then the regen wont trigger.

 

[j s pollo]

My Land Rover diesel you are warned about the soot build up problem short journeys cause soot build up and cause the Landi to go into limp mode .
What i do to prevent soot build up use redex and cat cleaner and give it a good blast down the motorway every 2/3 weeks to burn it off it has worked for me give it a try it may solve your problem at least you will have a clean engine.