Gen 3 Engine Managment light

Hi all, 
I'm getting frustrated and need some help. Vehicle is 03 plate M13A (non VVT) with an engine light that comes on every few hundred miles, OBD reports codes P0400
I'm a little up against time to fix as it's my sons vehicle and he has a driving test booked soon (no warning lights allowed), so far I've

- Changed O2 sensor 1
- Changed O2 sensor 2 + cat (but reads a flat 1.275 volts)
- Changed IAC
- Changed EGR valve
- Cleaned PCV value
- Changed TPS (this now only read 13%-78%)
To be changed this weekend are sparks plugs / coil pack

When cold the car needs some revs to pull away otherwise stalls. Drives perfectly when warm except occasionally when ticking over can hunt a bit (maybe 700-1100rpm)

Is there anything I've missed or does anyone have any other good suggestions?

Thanks in advance

Carl

The P0400 code has a specific definition, from the Jimny FSM this is "EXHAUST GAS RECIRCULATION FLOW MALFUNCTION", and the possible causes are listed as ...

EGR valve or it's circuit
EGR passage
ECM

Essentially, the ECM runs a test by commanding the ECR valve to open whilst monitoring the "pressure" in the intake manifold, and if the change in pressure is less than expected, you'll get this code.

The EGR valve could be not opening, because it's defective, you'll get the code; the EGR valve could be not opening because there's a problem with the electrical circuit, you'll get the code; the EGR valve could be not opening because the driver circuit in the ECM failed, you'll get the code.

The EGR valve could be opening and there is insufficient change in the manifold pressure because the EGR passage is blocked with carbon from the exhaust, you'll get this code.

My guess is your problem is the last, but it's just a guess.

Thanks for the quick reply.
I replaced the EGR valve, I guess I now need to remove the inlet manifold and pipe connecting the EGR and clean out. (I didn't do that previously as the old EGR looked pretty clean)

Thanks

Carl

You might want to take a look at the exhaust side as well - unless I'm very much mistaken the EGR system runs off the #4 exhaust port, through the exhaust manifold, through a drilling in the head and then out to the EGR valve.

Changed my throttle body other week 
I think I may have seen where it recirculates into the Inlet 
Maybe you could guide a thin wire in and give it a good wiggle 
Without removing Inlet manifold 

Just a thought 

Thanks for the advice. Day off today so will be taking it all apart and cleaning etc. fingers crossed.