Breezy_Pete

Shouldn't add any errors as long as ignition is off when removing fuses.

Check some fuses (on battery-top fuseholder) before you go a step further. Strip fuse No.4 would be my favourite for having a crack in the middle of it, that might barely be visible until unbolted. Blade fuses 7 and 10 should also be checked

There are two more sensors at the front wheels, which worsens your odds of a quick fix by blind replacement.

Please let us know the outcome. 🙂

I guess that looks encouraging, but if the check engine light was on, a code should have been stored. What made you think the tensioner failed? I could lend you the timing tool kit and potentially some help to use it if you're not too far from Highworth. Shall I start a PM chat with you?

I think a single-tooth skip might not be catastrophic on that, but I'm not sure. Whereabouts are you based? There's an inexpensive timing tool kit that could be used to check the current situation, but it needs a little effort and raising the car a bit off the deck to fit the crank tool.

Chain engines can usually be distinguished fairly readily by the chain cover being sealed (because it has to keep oil inside). Belt engines have looser fitting, unsealed timing covers.

Engine code is often on a sticker on the upper cambelt cover (for belt engines anyway). Also on V5. See: Engine code and why it's useful to know - Handy Topics & Guides - BRISKODA

The description of the windscreen for the provided VIN, of a car with heated windscreen is: "Heat insulating windshield". To me, that didn't sound like a convincing description of a heated windscreen, so I suggested that you might be able to confirm. PR code was 4GW. I have (paid) access to partslink24, but not always much knowledge about what I'm looking at.

Maybe measure the 5V supply that goes to both the EGR valve potentiometer and the MAP/IAT sensor. Red/green wire at each of those connectors, measure relative to the brown wire at MAP sensor, and relative to the brown/blue wire at EGR connector. Ignition/contact on, or engine running when measuring.

In a LHD car (steering wheel on the left) it is somewhere just above your left foot when driving. Onboard control unit is often called 'BCM'.

Does disconnecting the EGR plug generate fault code(s) and fault light? (asking @Erdmi )

Surely that would generate a fault code?

Yes, it causes owners in RHD countries plenty of head-scratching. Cost saving.

OK, I give up. ☹️

No, you just have a RHD car instead of the LHD the manual pictures. Fuesbox is just rotated 180°, in the factory.

Another possibility, I guess, is that the catalytic converter is blocked to some extent, causing the exhaust pressure entering the EGR valve to be higher than mapped. The feedback system for EGR opening is based only on physical distance, via a potentiometer in the top part of the valve. So more gas could be flowing through EGR into inlet manifold than expected, causing higher intake temps and poor combustion. How many kilometres has the car driven?

Does the engine ECU log any fault codes for EGR or anything else?

Labelled B above.

It's in the front half of the airbox, the section that does not need to be removed to change the filter. Wedging the flap in the cold air only position is probably the easiest solution, which can be done with a screw. Do the experiment first (running without airbox), I might be completely wrong about why the engine is having trouble.

Are you aware of the warm/cold air mixer system within the airbox? When the wax thermostat in there fails, it leaves the mixer flap in the 'maximum warm air' position. The combination of that unnecessarily warm air and hot EGR flow may be causing the problem.

Can you try running without engine cover/airbox for a short drive when engine is fully warm? See if fault still happens.

EGR flow isn't enabled until coolant temperature is above a certain point, maybe 50°C, Can't remember exactly, so that may be why it's OK when cooler.

Have you inspected the brake servo vacuum hose for cracks and leaks?