Engine Performance problem
2001 Toyota Corolla 4 cyl Front Wheel Drive Automatic 150000 miles
My wife's Corolla has "check engine" light. OBD ll displays code 0420. Catalyitc converter efficiency below threshold bank 1.
We have first replaced down stream O2 sensor, still have same code #. Next replaced catalytic converter, still have same code #. Finally replaced upstream O2 sensor and still have same code #.
Upstream O2 sensor voltage not changing much after engine is hot, with downstream sensor voltage changing alot. What is next to get replaced the car or the Engine Coolant Temperature?
have the same problem?
Wednesday, October 15th, 2008 AT 11:59 AM