*NOW BOOKED FOR 2026* Transitmania 17 @ Santa Pod 17th to 19th July 2026 *ALL DETAILS HERE*


Adblue light straight away on ignition on

Use this forum to post technical questions & problems about any Transit

Moderator: Luke

Re: Adblue light straight away on ignition on

Postby Frag » Sat Jan 10, 2026 1:37 pm

The Tank heater itself is the only thing that goes wrong in the tank in my experience.
I’ve had jobs like this,that come to us after multiple people have unsuccessfully tried to fix them,and had them in bits and fired the parts cannon at them,usually recovered in as non-runners and stripped down…

At that point,only way is to start from fresh as a new job.if you have no current DTCs to deal with immediately, the best way is to drive it and then see what issues need tackling.
Other than open circuits read by the module doing its own diagnostic self test,most issues or faults will not be logged until the system tries to operate.
It doesn’t activate until coolant and exhaust temp sensor reach preset parameters.(around 65 degrees coolant and 150 degrees on EGT 1)it will then run the SCR pump up to pressure and start dosing during acceleration.
Then the NOx sensors start to monitor efficiency to check system is working.
At that point if it’s not happy with anything it will then log the relevant dtc.

Unplugging any wiring or sensors will trigger the no start inducement countdown,(starts at 500miles)even if nothings wrong.
That will not clear until the system gets up to temp and completes a given time monitoring it working correctly.
User avatar
Frag
Ford Technician
 
Posts: 5092
Joined: Sat Jul 05, 2008 3:05 pm

Re: Adblue light straight away on ignition on

Postby Ryan9153 » Mon Jan 12, 2026 12:56 pm

Frag wrote:The Tank heater itself is the only thing that goes wrong in the tank in my experience.
I’ve had jobs like this,that come to us after multiple people have unsuccessfully tried to fix them,and had them in bits and fired the parts cannon at them,usually recovered in as non-runners and stripped down…

At that point,only way is to start from fresh as a new job.if you have no current DTCs to deal with immediately, the best way is to drive it and then see what issues need tackling.
Other than open circuits read by the module doing its own diagnostic self test,most issues or faults will not be logged until the system tries to operate.
It doesn’t activate until coolant and exhaust temp sensor reach preset parameters.(around 65 degrees coolant and 150 degrees on EGT 1)it will then run the SCR pump up to pressure and start dosing during acceleration.
Then the NOx sensors start to monitor efficiency to check system is working.
At that point if it’s not happy with anything it will then log the relevant dtc.

Unplugging any wiring or sensors will trigger the no start inducement countdown,(starts at 500miles)even if nothings wrong.
That will not clear until the system gets up to temp and completes a given time monitoring it working correctly.

So thanks Frag for the advice we are getting there, I took for a drive couldn’t get rid of adblue warning, but did then have a fault code exhaust temperature sensor 3 intermittent fault, replaced that sensor, took for another drive watched data and seen it doing a regen, once regen was done about 5 mins later adblue light went out and has not come back on, however I carried on driving to see if it was ok and then it seemed to not regen again and P0420:00-A7 and service engine now came on. Any ideas on this one bud.
Ryan9153
Transit Addict
Transit Addict
 
Posts: 41
Joined: Wed Dec 17, 2025 6:12 am

Re: Adblue light straight away on ignition on

Postby metalworker0 » Mon Jan 12, 2026 3:22 pm

3rd line down in my first answer to you .

all the best.mark
User avatar
metalworker0
Transit Extremist
Transit Extremist
 
Posts: 5610
Joined: Wed May 05, 2021 4:43 pm
Location: Prestatyn

Re: Adblue light straight away on ignition on

Postby Ryan9153 » Mon Jan 12, 2026 3:32 pm

metalworker0 wrote:3rd line down in my first answer to you .

all the best.mark

Your 3rd line says blocked dpf? Which it wasn’t that bud so I’m a little confused what do you mean? It could be a blocked cat? Not dpf is that what you mean?
Ryan9153
Transit Addict
Transit Addict
 
Posts: 41
Joined: Wed Dec 17, 2025 6:12 am

Re: Adblue light straight away on ignition on

Postby metalworker0 » Mon Jan 12, 2026 3:47 pm

replaced that sensor, took for another drive watched data and seen it doing a regen, once regen was done about 5 mins later adblue light went out


all the best.mark
User avatar
metalworker0
Transit Extremist
Transit Extremist
 
Posts: 5610
Joined: Wed May 05, 2021 4:43 pm
Location: Prestatyn

Re: Adblue light straight away on ignition on

Postby metalworker0 » Mon Jan 12, 2026 3:57 pm

I'm not having a go at you .. its just these systems work in mysterious confusing ways .. and defeat most mechanics even .. how people have spent thousands replacing addblue tank when it can be blocked dpf
How many people have spent hundreds looking for traction control and abs faults when the thing puts on a traction control warning, because it disables itself when there is a problem with the engine

no wonder , i say

all the best.mark
User avatar
metalworker0
Transit Extremist
Transit Extremist
 
Posts: 5610
Joined: Wed May 05, 2021 4:43 pm
Location: Prestatyn

Re: Adblue light straight away on ignition on

Postby Ryan9153 » Mon Jan 12, 2026 7:16 pm

metalworker0 wrote:I'm not having a go at you .. its just these systems work in mysterious confusing ways .. and defeat most mechanics even .. how people have spent thousands replacing addblue tank when it can be blocked dpf
How many people have spent hundreds looking for traction control and abs faults when the thing puts on a traction control warning, because it disables itself when there is a problem with the engine

no wonder , i say

all the best.mark

No I understand you weren’t having a go your answer confused me 3rd line down in my first answer to you was about the dpf, which it wasn’t to do with that, the dpf was not blocked, but it needed temp sensor 3 replacing for it to carry out a full regen which it did, but now it’s thrown another fault code for Catalytic threshold P0240 I think that’s the only fault code and on dash is service engine now, but with one turn of key it goes off, but comes back on when I drive it again, it’s not regenerating again as I can see the soot content building up it’s now around 110% so I’m back to the drawing board to find out what’s causing this fault code, could be nox sensor, cat itself, wiring etc, my next port of call is to find a diag that will read the o2 content before and after cat to see what’s going on. The adblue warning is def off and the warning for no start has gone, but I need to sort this before the dpf gets blocked.
Ryan9153
Transit Addict
Transit Addict
 
Posts: 41
Joined: Wed Dec 17, 2025 6:12 am

Re: Adblue light straight away on ignition on

Postby dumper » Mon Jan 12, 2026 7:49 pm

Have you had a look at O’Reilly autos on YouTube he is good at showing what can go wrong
2025 MK 8 L3 H3 Motorsport campervan
Past camper vans
1974 mk1 v4 with 2.0 pinto fitted
1986 mk3 2.5 di swb
1990 190 lwb 2.5 di
1998 100 lwb 2.5 di
2006 350 jumbo 135 tdci
2015 MK 8 L4 H3 motorsport campervan
dumper
Transit Extremist
Transit Extremist
 
Posts: 6323
Joined: Sun Jan 20, 2008 2:56 pm
Location: Lincolnshire

Re: Adblue light straight away on ignition on

Postby Frag » Mon Jan 12, 2026 8:10 pm

Have you checked the operation of the cooling system thermostat ?

They are really prone to sticking open,you won’t notice on dash / guage,But it won’t get above the 80 degrees required to allow a regen,and or won’t get hot enough to regen properly.

Very common problem on nearly all 2.2s and very much overlooked

Also P0420 can trigger when there is not enough of a temperature rise during regen,so that would tie in.
(As would a partially blocked vaporiser,which can also happen when thermostat isn’t working correctly,which is nearly always !!!!!)
User avatar
Frag
Ford Technician
 
Posts: 5092
Joined: Sat Jul 05, 2008 3:05 pm

Re: Adblue light straight away on ignition on

Postby dumper » Mon Jan 12, 2026 8:44 pm

Frag wrote:Have you checked the operation of the cooling system thermostat ?

They are really prone to sticking open,you won’t notice on dash / guage,But it won’t get above the 80 degrees required to allow a regen,and or won’t get hot enough to regen properly.

Very common problem on nearly all 2.2s and very much overlooked

Also P0420 can trigger when there is not enough of a temperature rise during regen,so that would tie in.
(As would a partially blocked vaporiser,which can also happen when thermostat isn’t working correctly,which is nearly always !!!!!)


My 2.2 with add blue had two thermostats replaced in 30 k miles
2025 MK 8 L3 H3 Motorsport campervan
Past camper vans
1974 mk1 v4 with 2.0 pinto fitted
1986 mk3 2.5 di swb
1990 190 lwb 2.5 di
1998 100 lwb 2.5 di
2006 350 jumbo 135 tdci
2015 MK 8 L4 H3 motorsport campervan
dumper
Transit Extremist
Transit Extremist
 
Posts: 6323
Joined: Sun Jan 20, 2008 2:56 pm
Location: Lincolnshire

Re: Adblue light straight away on ignition on

Postby Ryan9153 » Mon Jan 12, 2026 10:13 pm

Frag wrote:Have you checked the operation of the cooling system thermostat ?

They are really prone to sticking open,you won’t notice on dash / guage,But it won’t get above the 80 degrees required to allow a regen,and or won’t get hot enough to regen properly.

Very common problem on nearly all 2.2s and very much overlooked

Also P0420 can trigger when there is not enough of a temperature rise during regen,so that would tie in.
(As would a partially blocked vaporiser,which can also happen when thermostat isn’t working correctly,which is nearly always !!!!!)

This I believe is a great shout Frag as when I was watching the engine temp while driving I kept thinking why is the temperature so low always around 65 degrees, will take a look at that tomorrow cheers bud.
Ryan9153
Transit Addict
Transit Addict
 
Posts: 41
Joined: Wed Dec 17, 2025 6:12 am

Re: Adblue light straight away on ignition on

Postby Ryan9153 » Mon Jan 12, 2026 10:14 pm

dumper wrote:
Frag wrote:Have you checked the operation of the cooling system thermostat ?

They are really prone to sticking open,you won’t notice on dash / guage,But it won’t get above the 80 degrees required to allow a regen,and or won’t get hot enough to regen properly.

Very common problem on nearly all 2.2s and very much overlooked

Also P0420 can trigger when there is not enough of a temperature rise during regen,so that would tie in.
(As would a partially blocked vaporiser,which can also happen when thermostat isn’t working correctly,which is nearly always !!!!!)


My 2.2 with add blue had two thermostats replaced in 30 k miles

Good shout I think bud going to try this tomorrow and let you know.
Ryan9153
Transit Addict
Transit Addict
 
Posts: 41
Joined: Wed Dec 17, 2025 6:12 am

Re: Adblue light straight away on ignition on

Postby Frag » Mon Jan 12, 2026 10:28 pm

Thermostat should open at 88 degrees,so ECT should never really be below that once warm and when driving.

When stat is stuck,you’ll struggle to get it warm even if revving it stood,and once you do,when you drive it will then drop quickly,especially this time of year when ambient air temp is so low.

Causes all kinds of issues,stops regens,engine wear,poor economy and the ECU needs to see engine hot to class it as a ‘drive cycle’

Also,from dealers,the thermostat itself on its own,is more expensive than the whole housing including stat and temp sensor :shock:
User avatar
Frag
Ford Technician
 
Posts: 5092
Joined: Sat Jul 05, 2008 3:05 pm

Re: Adblue light straight away on ignition on

Postby Ryan9153 » Tue Jan 13, 2026 2:05 pm

Frag wrote:Thermostat should open at 88 degrees,so ECT should never really be below that once warm and when driving.

When stat is stuck,you’ll struggle to get it warm even if revving it stood,and once you do,when you drive it will then drop quickly,especially this time of year when ambient air temp is so low.

Causes all kinds of issues,stops regens,engine wear,poor economy and the ECU needs to see engine hot to class it as a ‘drive cycle’

Also,from dealers,the thermostat itself on its own,is more expensive than the whole housing including stat and temp sensor :shock:

Hi Frag again appreciate all your knowledge, so thermostat was def an issue because now my temp stays up around the halfway mark whereas before never got much past 65 degrees. But I’ve driven her for ages now and she starts the regen gets about half way through, then I get the service engine now and the catalyst efficiency below threshold fault code which stops the regen. If I clear the code and drive again, it will start another regen but gets to roughly the same point around 55% soot and 5% inferred loop then it throws the fault and stops the regen. Any ideas bud possible nox sensor you think? It’s only don’t 55k miles.
Ryan9153
Transit Addict
Transit Addict
 
Posts: 41
Joined: Wed Dec 17, 2025 6:12 am

Re: Adblue light straight away on ignition on

Postby Ryan9153 » Tue Jan 13, 2026 2:08 pm

Ryan9153 wrote:
dumper wrote:
Frag wrote:Have you checked the operation of the cooling system thermostat ?

They are really prone to sticking open,you won’t notice on dash / guage,But it won’t get above the 80 degrees required to allow a regen,and or won’t get hot enough to regen properly.

Very common problem on nearly all 2.2s and very much overlooked

Also P0420 can trigger when there is not enough of a temperature rise during regen,so that would tie in.
(As would a partially blocked vaporiser,which can also happen when thermostat isn’t working correctly,which is nearly always !!!!!)


My 2.2 with add blue had two thermostats replaced in 30 k miles

Good shout I think bud going to try this tomorrow and let you know.

So def improvement on temperature now staying at around centre of gauge, but still throwing the catalyst below threshold code after a driving trip and it’s stopping the regen from completing. Any ideas bud?
Ryan9153
Transit Addict
Transit Addict
 
Posts: 41
Joined: Wed Dec 17, 2025 6:12 am

PreviousNext

Return to Technical Problems & Questions



Who is online

Users browsing this forum: No registered users

This site contains affiliate links for which we may be compensated.