Hello guys, need some help with this returning issue. P0400 faultcode keeps coming back after erasing the code. It revers to the EGR-valve, but can also come from vacuumleaks / faulty MAF sensor.

done so far:
- Fuelsystem cleaner added, also directly on the EGR opening under the accelaratorvalve (i removed the complete unit)
- checked the EGR pipes for possible leaks
- replaced the MAF sensor for a new one.
- repairset placed for the mounting of vacuumline from manifold to brakebooster. (Copper Bush and o-ring)
- checked most of the hoses for possible breaks or leaks.
- fixed one connection of hose on the manifold to the breather on the valvecover.

what to do next?

the mil light turns on after a longer period of driving, sometimes long and sometimes shorter time.

when the light is on i have the feeling that the engine is not running so smooth as with no error. Also i have the feeling that the automatic gearbox shifts diverend with the p0400 error stored. But maybe the engine is taking a standard mapping when a fault is stored.

when i drive the car normally i noticed when giving a little gas on low revs, that the rpm is fluctuating/not stable. Changes up and down about 750 revs.

this could be another problem that has to do with the torque converter that is beginning to get faulty?

read someting about the bypass valve for the supercharger, the actuator can leak? In witch position is the valve open with vacuum on it or when in rest? Maybe i can bypass it to shut things out?

sorry for my bad english, al tips and hints are welcome.

Greetings,

Arian Vos

 

Sorry to hear of your troubles. The car's model year and engine type might prove helpful in sorting this out...it looks like you have an STR with the supercharged V8?

 

Thats right i have an 2003 build jaguar s-type R sorry i did not mensioned it in the first place.

greetings Arian

 

 

Scan for correct MAP sensor function. In my case I was getting a P0400 EGR code (but strangely no MAP codes) because of faulty MAP function. The MAP sensor port is located next to the EGR port in the elbow. The EGR monitoring process commands full EGR during sharp deceleration (when driveability isn't affected) and if the MAP sensor doesn't pick up a pressure pulse you'll get the EGR code.

If anyone has been working in the elbow area previously they may have broken the MAP wiring connector. It's way too short and impossible to see. A sharp jerk on the elbow while removing it will do it.