my check engine light was on, and after going to a auto shop and had them read the obd code for me. i found out it's turned on because it has problem with transmission(1739) and catalyst converter (420).
i have a honda accord le 1998 4 cyl with 82k mileage. any suggestion what should i do next. i already had mechanic to turn off the check engine light.

 

I WAS TOLD IT WAS A 3RD CLUTCH SWITCH IN THE TRANSMISSION. IS YOUR CAR HAVING TROUBLE DOWN SHIFTING WHEN YOU COME TO A STOP SIGN AND DONT COME TO A COMPLETE STOP THEN TRY TO TAKE OFF?

 

PO420 is activated when the secondary O2 registers that the catalyst is falling below acceptable threshold of emissions output. This does not necessarily mean the catalyst itself is failing, but that the emissions are higher than anticipated.

If the primary O2 is old/lazy it may not be keeping the engine running at stoich. Also if the car is well overdue for a tuneup then this would also cause emissions issues.