My C4 Grand Picasso Nightmare

This is the Forum for all your Citroen Technical Questions, Problems or Advice.
Mattb1983
Posts: 3
Joined: 27 Oct 2025, 09:00

My C4 Grand Picasso Nightmare

Unread post by Mattb1983 »

This is the story so far 

The Mrs has a 2009 c4 grand picasso it's been a wonderfull car until now....

Driving home one evening it flashed up with environmental system fault and went into limp mode assuming it was dpf/egr related and having had a living hell with my zafiras dpf we made the decision to have the dpf and egg deleted and the car remapped 

Now the car will randomly go into limp mode no fault codes or eml light or anything just limp mode and you have to pull up turn the car off and on and it will drive fine for a while 

If anyone can help I'll be forever in their debt 

It's had the injectors resealed recently and a new MAF sensor the other day 



Many thanks matt
User avatar
mickthemaverick
Moderating Team
Posts: 20152
Joined: 11 May 2019, 17:56
x 7789

Re: My C4 Grand Picasso Nightmare

Unread post by mickthemaverick »

We cannot comment on your car in view of the modifications you have done. :)
I used to be indecisive, now I'm not so sure!
I used to ride on two wheels, but now I need all four!
PaulC5
Donor 2024
Posts: 2285
Joined: 06 Jun 2023, 15:26
x 569

Re: My C4 Grand Picasso Nightmare

Unread post by PaulC5 »

Take it back to where the mods were done, they may be the only ones who can help. Also see if they can put it back to normal and make it legal again. The original fault may not have even been anything to do with the dpf and egr unless you had a full diagnostic done.
shtu
(Donor 2023)
Posts: 225
Joined: 09 Dec 2023, 16:19
x 54

Re: My C4 Grand Picasso Nightmare

Unread post by shtu »

About the only thing I can suggest is that some scan tools are absolutely rubbish at reading Citroens. I've a cheap ELM327 and a Diagbox, and the ELM327 can be relied uopn to be a flaky piece of nonsense.

Beyond that, the advice above holds true. Essentially impossible to offer any advice as they've removed components and done lord knows what to the car's systems.
Mattb1983
Posts: 3
Joined: 27 Oct 2025, 09:00

Re: My C4 Grand Picasso Nightmare

Unread post by Mattb1983 »

To put it back to manual standard is it as simple as put new dpf and egr then remap
PaulC5
Donor 2024
Posts: 2285
Joined: 06 Jun 2023, 15:26
x 569

Re: My C4 Grand Picasso Nightmare

Unread post by PaulC5 »

Possibly but if you did not remove the egr or damage the dpf by knocking a hole through it then they may still be ok to use. If whoever did the remap does not have access to the original ecu software then it might need to go to a dealer for that. You then have the original fault that may still need fixing.

Note that if you have not already informed the car insurer about these mods you might find your insurance is not valid if you make a claim. With the mods they may not cover your car since it is not up to MOT standard.

When fitting new parts sometimes copy ones do not work as well as ones from a dealer so cheap is not always best, just a comment in case the new problems started after you replaced the MAF. It is always best to have a diagnostic before replacing parts if you have not been doing this since trying to solve a fault by fitting lots of parts hoping to guess correctly can be expensive.
User avatar
Mihael_M
Donor 2024
Posts: 176
Joined: 14 Aug 2024, 18:58
x 34

Re: My C4 Grand Picasso Nightmare

Unread post by Mihael_M »

Is the new sensor original PSA or aftermarket? I have had bad experiences with aftermarket new sensors.