I have a Ford Focus 2010 1.6Tdci with a long-standing loss of power issue after approx 30 mins of drive which sends into limp mode. Always resets to normal power after restarting engine and the cycle goes round and round. 

In March this year had engine light codes of P0490 & P042F so replaced with a new EGR upon mechanic advice (cheap option EGR bought vs premium). No improvement on loss of power. Now engine light on again with same two above codes. Taken to a different garage as first couldn’t diagnose issue. They tested EGR and voltage values etc and suggest replacing with a premium EGR. My worry is spending all this money and the issue of loss of power will still be there. Any suggestions/advice would be much appreciated. 

 Attached are original and now most recent engine codes pics. 

Check the MAF signal. I have the same problem. I got no error on MAF but there's no signal from it to ECU . At idle i have 9g/s and it should be around 1g/s . worth to check. My EGR also stucks after 30 - 40 seconds. 

Thanks for the reply mate. I’m not very good with car parts etc so I can ask my mechanic to check. What’s the solution? Have you sorted yours ? 

Also why would it repeatedly bring about an EGR fault code rather than MAF one or any other?

Ok, im not a specialist but i think the MAF and IAT sends command to EGR to open and close. I'm not really sure, but take my case for example, i got no error on my MAF sensor but theres no signal to ECU and the EGR stucks after 30 - 40 seconds . Or maybe, in your case the EGR is the problem. Don't buy cheap parts.

Hi there, just wondered if you found a solution to this in the end?