About 18 months ago I had a service done by a private garage (non Volvo authorised) and the timing belt was changed.

Sometime since then I have been receiving an engine emission warning. No on permanently

The local volvo specialist (again private) seems to think the codes indicate a cam position problem ( and not the o2 sensors).

Could changing the timing belt have caused this problem.

How easy is it to a/ check the belt b/ reset the timing belt.

 

What codes were pulled?
Yes having the belt off by one or 2 teeth can set a code. But it would be a VVT code.
Then belt isn't all that hard to check. Remove the Top spark plug cover then the outer cover and you can inspect the belt.

 

The first time I replaced the belt on my wife's car, 2001 V70XC now 146,000, the cogged belt was off. By how many teeth I didn't know. I went in and moved the belt one tooth. Wrong! Went back and changed it two teeth in the other direction. Bingo
When the belt is off. idle is extremely erratic.

Good luck

 

If the belt was done a year and a half ago, and you didn't see the ESS warning until MUCH later, then don't suspect the timing belt jumped. If the tensioner wasn't torqued correctly, you would have had camshaft position codes popping up rather quickly. You left off a letter in your statement, "No? on permanently" Was that for Now or Not?

Ah, does the shop not KNOW what the codes indicate? Have them relay the codes to you and post back.

I hope that I understand your facts as you've laid them out...