I started the car yesterday and get the yellow triangle of doom together with “Restricted Performance” message. Limped the car home and plugged in my Carly dongle. It came up with the code p242a bank 1, sensor 3 exhaust gas temp. I had noticed for a while that it did smell a bit exhausty inside the car. The fault clears if I shut down then restart the car. It does return once it’s been sat a few hours.

My 13 year old noticed fumes coming out of the top of the engine when we had the bonnet open. He crawled underneath and saw the fumes looked like they were coming from the area of the C clip where the exhaust bolts onto the turbo. As he’s smaller and got longer arms than me he tried to tighten it up but it was just too fiddly.

My questions are: is it easier to access the clip from the top of the car by removing the window scuttle and the panel behind the engine or should we go through the wheel arch?

Should I change any kind of gasket whilst there?

Is a loose c clip the likely candidate for the exhaust gas escape?

In anticipation, thanks for your answers and suggestions.

Well, got back from an early shift at work in limp mode. Decided to go for an afternoon nap. Meanwhile my 13 year old decided to have the engine bay in bits and tackle it from the top. He only went and fixed the problem!!! The c clamp hadn’t been tightened properly and had vibrated off. He’s a good lad and has saved me hours of time and money! On the negative side, I’m going to have to pay him 😖

The exhaust fumes have disappeared from the cabin but on start up this morning: yellow triangle, Restricted Performance message, limp mode and P242a exhaust temp sensor code. Any other suggestions or should I go straight in and change one/both sensors? I see that I should change both as either can throw up the fault? I notice it happens on chilly mornings (about 6 deg here) and plenty of dew around.

I did notice that the downstream sensor had a small knick in the blue cable. I’ll have a proper investigation later.