On a 2003/03 Audi A6 1.8 se sport what are the

Not all fault codes are genuine , you are best to hook car up to an OBD2 reader and clear codes first , if code re-appears investigate further , some codes are ghost codes or old codes stored

yes a new belt should have a new tension other wise they cant guarantee the belt will last another 90k miles because in the old tensioner loosing tension and possibly damaging the new belt

The timing must be off. There is a crank lock that must be installed when changing the belt and also a holding "jig" that holds the cams in place while you are changing the belts. Also the cam pulleys must be separated and free from the cam shafts when installing the belt and tensioning in order for the engine to be timed correctly.

to be sure, have someone bump the starter while you watch the belt. It will usually not turn the wrong direction. Another way to tell is where the tensioner is located (assuming only one tensioner) . The crank gear must pull the belt directly to the cam

If it's anything like the six cylinder engines from Audi, which I'm very familiar with, and from what I remember of the V8, you have a timing belt that drives the water pump, crank, and exhaust cams, and also includes a tensioner and an idler roller. The timing chains come into play in the cylinder heads. What Audi did was to only drive the exhaust cams off of the crank, using the timing belt, and inside each cylinder head there is a timing chain assembly that is used to drive the intake cams off the exhaust cams. On a periodic service (like the timing service) you only need to do the timing belt. The timing chains are only replaced if the tensioners fail - you'll know this by a diesel-like clatter from the cylinder heads. Failure of the chain drive assemblies is very rare, which is good because they're incredibly expensive (on the V6 engines they're upwards of $700 each). If you're doing this job because it's due based on mileage, don't touch the timing chains in the cylinder heads - only change the timing belt, tensioner roller, relay arm, hydraulic tensioner, idler pulley, water pump, and serpentine belt. You can leave the chains alone.

Did you try www.autozone.com? Might help

Audi A3 Recommended Tyre Pressures 1.6 96 - Onwards 28 28 32 40 1.8 96 - Onwards 28 28 32 40 1.8 SE 96 - Onwards 28 28 32 40 1.8 Sport 96 - Onwards 28 28 32 40 1.8 T Sport 96 - Onwards 28 28 32 40 1.8 T Quattro Sport 00 - Onwards 28 28 32 40 S3 99 - Onwards 30 30 36 40 1.9 TDi - 110bhp 96 - Onwards 30 30 36 40 1.9 TDi - 130bhp 01 - Onwards 28 28 32 40

no all audi TDI have a T belt which have to be changed every 60,000 miles

There is no change interval as it is chain driven

The 1.8T is very common in the US. We don't have any diesels here in the A4, but the 1.8T is all over the place.

What exactly do you need to know? You were posting it in the title to your question but it got cut off and I don't know exactly what you're looking for in terms of info for changing the cam chain. If you mean the timing belt, that's a belt, not a chain. I thought that the 1.8T drove both cams off of the belt, unlike the 2.8, where only the exhaust cams are belt-driven by the timing belt, and the intake cams drive off their respective exhaust cams via a chain and tensioner assembly. If you can clarify this, we can proceed.