Wednesday, April 18, 2012

1996 Jaguar XJS I6: P0400, P0420 and P0430

So today I got an 1996 Jaguar XJS with the codes:
The P0400 code is for the EGR temperature sensor which is showed in the next pic.

Basically, when the car's EGR valve opens, it recirculates exhaust gases and directs them to the intake manifold. In this process there is a temperature sensor that expects to see a change in temperature when the valve opens. Here are some pics of the EGR valve:

This code could be caused by a number of reasons, bad EGR valve, plugged piping, bad sensor, fouled sensor, etc. The most common reason though, in my experience, is a plugged pipe (the one showed in the next pic). In the picture, i'm strawing it out with a clothe hanger and some carburetor cleaner.
After putting everything back together and clearing the faults the P0400 was gone but the other two codes came back after test driving. Replaced the upstream oxygen sensors and the problem was solved.


  1. Have the P0420 and P0430 codes stayed away after several miles?

  2. I have a 1996 Vanden Plas and im tryin to clean egr pipe. How do i clean it without taking it off?

  3. The main function of the EGR or the exhaust gas recirculation valve is to reduce oxidation of nitrogen through the reduction of combustion temperature. The combustion temperature can only be reduced when the EGR valves send some of the exhaust gas through the intake manifold back into the cylinders. When the combustion temperature is very hot, there is a reaction between nitrogen and two other byproducts, and this process forms nitrogen oxide. When this nitrogen oxide is released into the atmosphere, it mixes with oxygen and becomes nitrogen dioxide. When nitrogen dioxide combines with other compounds like hydrocarbons in the presence of sunlight, smog is formed that is basically a pollutant. Click here and get EGR Delete Kit for EGR removal.

  4. I have a 95 XJ6 VDP. How did you clean the EGR pipe? There is no way of getting all the built up carbon out of the pipe after you scrape it down with a coat hanger. It will just get sucked into the exhaust and mess up the CAT won't it?