P0420 and P0015 "B" codes returned on 2003 Volvo S40 during emissions test

OK my mechanically inclined friends. My 2003 Volvo S40 Turbo (140K miles) came back with the following during emissions inspection (and failed). Any idea what this will cost? Is it worth fixing?
P0420 Catalyst system efficiency below threshold - bank 1 and
P0015 “B” Camshaft position timing over retarded - bank 1

The P0420 code is most likely a bad oxygen sensor downstream of the catalytic converter. Have the sensor replaced, NOT the catalytic converter. And yes, you should fix it.

This website should give you an estimate for that repair cost in your area: www.repairpal.com.

Don’t know about the P0015 code but someone esle here will.

agree with jesmed on the P0420. For the other code, you may need a mechanic to check your cam timing. If you are due or overdue for a new timing belt, just plan on getting that done before the belt lets go an ruins your valves. If you just had it done, take it back because the mechanic didn’t do it right.

The P0420 code might be caused by the P0015 code. The P0015 code is caused by a problem in the Variable Valve Timing. And if the valve timing is off the catalytic converter may not operate efficiently.

The P0015 code could be caused by a defective camshaft reset valve. Takes about fifteen minutes to replace. If the code returns after replacing the VVT reset valve, then more than likely there’s a problem with the VVT hub. This requires partial removal of the timing belt in order to replace the hub.