Question

1998 Saturn SL2 two codes p0340 and code p0420 are they related in some way. Thanks

Answer 1

Yes they can be related a P0340 is camshaft position sensor "A" which is the sensor itself, and P0420 is catalyst below threshold, in other word a cat to be effeicient need to run lean and switch back to rich,in order for it to function but it stays on the lean side,Once camshaft position sensor codes up the ECM default to a value to protect the catalytic,so yes it can be related,so you need to fix the camshaft sensor problem clear the code and go from there,also have the timing belt inspected

Answer 2

e test says camshaft possision sensor bank1 a circuit range performance bank 1 or singles . also saysp420 catalystsystem efficiency below threshold bank 1.

Answer 3

P0420 SATURN - Catalyst System Low Efficiency Bank 1
Read more: https://www.autocodes.com/p0420_saturn.html

P0340 SATURN - Camshaft Position Sensor 'A' Circuit Malfunction
Read more: https://www.autocodes.com/p0340_saturn.html