Hey folks, I have a '95 MK8 w/ about 136000 miles on it and recently got a couple of codes. P0538- A/C Evaporator Temperature Sensor Circuit High Input and P0412- Secondary AIr Injection Solenoid Circuit Malfuntion that intermittently came on at the same time. About 2-3 months ago I took into dealership for valve replacement and replaced the plug wires myself (they said I missed the order on 2 which I think is odd since I followed how the car was at first and what both lincoln and chilton manuals said the firing order was) sorry a bit off topic. Anyways...

So what would be the list of things that could cause these 2 to come on and what of them would be related to Iso. the issue?

you sure those are the right codes?

those are OBD2 codes and a 95 is not OBD2

did the error codes come up after you replaced the wires or after someone fixed the order of the wires? And maybe the wires are not dressed where they should be and setting off the errors?

plug replacement - it seems a couple of manuals were either misleading (the way they show a wire view and you have to follow over and under, etc.) or appear incorrect. If you clean the top of the two coils up front they have the destination cylinders right on the coils. since they are interchangeable you just have to follow the numbers for which side of the engine. I think the driver side is the white numbers in the black circle.