Just looking for info
Check engine light came on a few weeks ago. Not sure what the code was, but mechanic said I need to replace the gas cap. Purchased one and installed. Light came back on yesterday and he said it was the same...bad fuel cap. Any ideas

 

post the code that set, your model year and engine size.
The " checkfuel cap" light/message sets when the evap system detects a large leak after a fueling event...doesn't mean the leak is from the gas cap. testing needs to be done...throwing a fuel cap on it is a shot in the dark. Fuel caps probably fix this 10% of the time.

 

Post the exact code. If it is a gascap code, 99% of the time, only using an OEM cap purchased from the dealer will cure it.

 

Check engine light came on again. Code is P0456...Any ideas?

 

 

Thanks for the link JKeaton. Question....This is a daily driver to work, but not alot of miles. Live 2.5 miles from work. Will this be a problem or do I just have to deal with the check engine light? We do not have emissions in my county

 

 

once the temps get cold enough the evap monitor won't run.
the code is for a small evap leak. 3rd gens could use 2 different type evap systems...depends on your model year...the systems work different so some of the testing is different.
the first step would be a flow test using a smoke machine.....with a sealed system the flow meter check ball should fall below the allowable flow rate...if it does, there is no leak...the fault could be a issue with the esim.

 

make sure you purchase a original manufacture gas cap, don't go aftermarket, if light still comes on, fill truck with 92/93 octane and run it for a few miles, preferably highway, being so close to work things might not be getting up to temp and working.

 

how does changing the fuel octane effect the evap system monitor? If its an esim equipped system the passive test runs overnight after the truck is shut down.