Originally posted by projectSHO89:
A loose gas cap will not cause a P0420 code. It will cause a P0455 (Gross Evap Leak) code.

If that "expert" with the fancy code reader understood how the OBD-II Cat Efficiency Monitor test worked, he would never have told you that. He also would have told you about "Drive Cycles" and why they are important in when certain tests will be run.

Take the car on several more trips and see when the code comes back. Cyling the ignition several times will not cause the apprpriate internal tests to be run. If you were to have the codes scanned right now, you would likely have a pending p0420.

Steve




I thought about those same concerns that you have, but I have driven my SVT for the past three days and the check engine light has not returned - and the light correctly cycles during start up. Also, I didn't just cycle the engine when I said it was started up 5 or 6 times, those were various start ups after stopping at the store, a friends house, etc. To this day since purchase my car has run the same, powerful and perfect - no changes or drop in horse power, fuel use, or poor operation. Whether the gas cap was correct or not, the fact is the cap was not on all of the way. The thing is, something trigered the sensor, whether it was the cap, a high powered excelleration, or even a bad batch of fuel, the point remains it hasn't returned and it is possible that this reading was trigered by accident or in error.

I know from years of experience with my home computer and office computers that system errors take place weekly, sometimes daily. That same technology is also in the car computer which also could have been created in error. It can be frustrating at times, but remember - computers are only has full proof as the humans that design them.

Fruit for thought: LOW Tech is sometimes better than NEW Tech. New technology computer equipment is unbelievable in speed and service, but also more open to damage and error. This is one reason why NASA uses older 8088 and 286 computer equipment in the space shuttle and planetary probes, they're stronger and hold up to riggerous elements such as launch, heat, cold, and extreme vibration. And though a car is not launched into space, it does face elements such as starts and stops in traffic, chuck holes, heat, cold, vibrating stereos, power surges, and an open end variety of radio signals, microwave transmissions, and cell phone transmissions. Unless the operation of your car changes, there's always the possibility or computer error.

Thomas

I Live My Life A Quarter Mile At A Time... During That 10 Seconds Or Less, I'm Free! 1998.5 SVT Contour aka: THE TOURMINATOR