OBD problems, code P0442

Tiny
4.7 GRAND
  • MEMBER
  • 1999 JEEP GRAND CHEROKEE
  • 4.7L
  • V8
  • 4WD
  • AUTOMATIC
  • 125,000 MILES
Hello there, so I noticed few months ago the OBD drive cycle was not done it said one incomplete and I noticed it said catalyst, but a code every so often pops up like barely comes on but maybe once or two times a month. I clear it and check again few days later and same thing one incomplete. The light will not come on few weeks even like a month of so will not come on when it does I get the code of p0442 small EVAP leak. I changed the purge valve and reset the computer, then few days later checked the OBD said it had seven complete zero pending. So I thought purge valve fixed it, but I got the purge valve from a junk yard, so I do not know if the purge valve is the problem. I do not see any holes in hoses. I smoked it out. No leaks. I do not know what is wrong. P0442 and catalyst will not complete. Has rough idle, idles at 600 rpm then some times just drops to like 500 490 then back up to 600. It has brand new crank and cam sensors. Drives great runs good. I do not know what to do, lol.
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Wednesday, July 18th, 2018 AT 10:27 PM

1 Reply

Tiny
KEN L
  • ADMIN
Hello,

I would start with a tune up and clean the throttle bore for the rough idle. The drive cycle issue can be caused by a stuck open thermostat which inhibits cycle time restrictions.

I would check the thermostat first. Here are guides to help you get started. Use OEM tune up parts:

https://www.2carpros.com/articles/how-to-tune-up-a-car-engine

and

https://www.2carpros.com/articles/throttle-actuator-service

and

https://www.2carpros.com/articles/replace-thermostat

Please run down these guides and report back.

Cheers, Ken

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Friday, July 20th, 2018 AT 11:12 AM

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