My car is showing a 'check exhaust emission' light - what should I do?

I have a 2008 Renault Koleos 2.0d. In the past two weeks I've done four journeys in excess of 50 miles at high speed (dual carriageway). A couple of days ago, a warning appeared saying "check exhaust emission" with the engine symbol and spanner symbol lit up and the vehicle had very little power. This morning I did a very short journey and when I restarted the car the only warning was the engine symbol being lit up. I did about 40 miles at high speed and the car performed normally but the engine symbol remained lit up. I got home, switched off and switched back on and the "check exhaust emission" warning came back on as did the engine symbol and spanner symbol. The car has done approx 75,000 miles with a mix of short/medium journeys and some longer trips. Have you any thoughts on what my next move should be?

Asked on 4 January 2018 by Bruno01

Answered by Honest John
I'd guess that the DPF is finally filling up with ash, which impedes its ability to regenerate as much soot. If I'm right, one solution is to send the DPF away to Ceramex to be chemically cleaned, which costs £300 - £400. The more expensive solution is a new DPF.
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