I have a Vauxhall Astra-h 1.4 Z14XEP.

Customer complained of engine juddering, and finaly the engine light came on to give me a point in the right direction.

Fault code P0400, Egr range or performance.

I quickly found a visable fault at the egr valve/actuator. 2 0f the 5 wires at the plug were shorting against each other. in the plug.

I repaired this and the engine really came to life. I could see the difference in the paremeters from graphing.

A couple of hours after this fix the customer complained of juddering again.

I graphed the car again, to get usable live data. I was going to view the results at home but got called back out as the engine management light had came on.

The same fault code P0400.

I graped the car again and have viewd the data. Sadly i don't know how to upload the results.

Basicly I am seing different results in the EGR feedback in volts. On some drive cycles the signal switches once from 1.2 v to 1.3 when other parameters are switching away and on 1 drive cycle the feedback volts goes as high as 4 volts with other parameters no different than before.

I am going to change the EGR vale, but beforwe i do this I like to turn to the UKAT guys.