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Jim Grant Tech Tips Jim Grant Tech Tips
A collection of helpful articles based on reader submissions
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Below is a collection of Jim Grant's Tech Tips sorted by Vehicle Make. These Tech Tips were answers to questions submitted to Jim by users over the course of many years.
If you have any questions, please feel free to email us.



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  Jim Grant's Tech Tips

00 Dodge Dakota, Check Engine Light Code P0442

Q: I have a ‘00 Dodge Dakota with 3.9 V-6. The check engine light came on and the code is P0442 (leak in the evaporative system). Other than the gas cap, oil dip stick and evaporative canister what should I check?

- Dan

A: The Diagnostic Trouble Code (DTC) # P0442 is the computer reporting that there is a leak in the evaporative system that is in the area of 0.040” of an inch. To give you some idea of what 0.040” looks like just check out the ball of a Bic ball point pen. It’s just a bit bigger than that. Now, what is an evaporative system? Gas loves to evaporate, just pull your gas cap off your car and note how quickly you can smell the gas when standing 2 to 3 feet away. What you’re smelling is your gas (money) evaporating floating off into the air. At first you may think that’s not a big deal. But it is! If you drive your vehicle with the gas cap off it will pollute way more than if it was driven with the cap on. That’s how clean today’s vehicles run. Gas just loves to evaporate! Have millions upon millions of vehicles doing the same thing and the gallons of wasted fuel and pollution in the air would just be astronomical! The evaporative system on your vehicle needs to be repaired. A leak that small is hard to find, yet we have tools, such as smoke machines to diagnose/find leaks in the system. The evaporative system starts at the gas cap and ends at the engine. In between there are plastic and rubber hoses, a few solenoids, a charcoal canister to store gas vapors, and in your vehicle’s case a Leak Detection Pump (LDP). Simple checks start with inspecting the sealing ability of the gas cap. Check the plastic vapor lines for damage or chaffing. Look for cracks in the rubber hoses and that all the components are correctly connected. If you think you found the problem all you have to do is drive your vehicle for a few days. If you repaired it correctly the computer will run its diagnostic test and turn the check engine light off. If not you’ll have to go to a shop that has invested in the diagnostic equipment, information and training to correctly repair your evaporative leak.

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