1999 Dodge Dakota 6 cyl Two Wheel Drive Automatic 107, 00 miles
After operation @ highway speed, If O have to immediately drive slow (e.G. If I get caught at a red light at the end of an exit ramp) my 1999 Dakota 3.9l check engine light comes on. A scanner reveals trouble code P0420 catalyst efficiency below threshold. If I get off the highway and am able to continue travelling at nominal speed (35-40mph)no light occurs. Likewise once the code is reset, the light may stay out for a month or more until the highway to slow speed condition is repeated. Catalytic converter (entire exhaust) was recently replaced due to rust out, but the intermittent trouble light remains. I'm guessing a bad O2 sensor, but would prefer to get some collaboration before I start randomly changing parts. Otherwise the vehicle performance and economy are unaffected by the presence of the check engine light.
Wednesday, July 29th, 2009 AT 12:55 PM