Interstar diesel particulate filter pressure too low

I had something similar with my Interstar a while back. Same symptoms - the light, the lack of power, the smell. I eventually figured out what it was. Have you checked the exhaust back pressure sensor? Mine was giving dodgy readings, and it messed everything up. The ECU wasn't triggering DPF regeneration properly.

The exhaust back pressure sensor, you say? Whereabouts is that located, and how difficult was it to swap out? I'm no mechanic, but I'm handy with a wrench, so would like to fix it myself if it saves on the repair costs at the shop. And how did you confirm that was the cause?

Location depends on your engine layout, but it's usually somewhere close to the DPF itself in the exhaust system. Unless you've got the right diagnostic gear, you're better off getting a professional to check it out, and possibly replace it. Could be a faulty sensor, a blocked pipe leading to it, or even the DPF itself failing. In my case the exhaust back pressure sensor was the reason for this behavior. I only found it after the guys in the shop did a thorough investigation.

Sounds like this is beyond my basic tools. I'll book it in with a local garage and tell them to check the exhaust back pressure sensor and the DPF system. Hopefully, it's just the sensor, I saw some online for around 60 quid. Shop confirmed: the sensor was busted. New one fitted, plus diagnostic and reset = 245€. She's purring like a kitten again! Thanks again for the advice!