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Dan, Technician
Category: Chevy
Satisfied Customers: 24584
Experience:  Independent Shop Experience, 2 Year Automotive Diploma, & Access to Information Database
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Working on a 2013 Chevy express 3500 with a 6.0 L gas

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Working on a 2013 Chevy express 3500 with a 6.0 L gas engine. Check engine light is on pulling code P0455 and P219A

Hello, my name is ***** ***** I'm here to help get your problem solved.

P0455 means you have a evap leak, usually means the purge solenoid, vent solenoid, or gas cap is leaking in that order. P219A means fuel trim is lean which would indicate a vacuum leak, here is a list of things to check. Let me know if you have questions, thanks.


  • Inspect the air induction system for modified, damaged, leaking, or restricted components.
  • Inspect the crankcase ventilation system for improper operation.
  • Inspect the vacuum hoses for splits, kinks, and improper connections.
  • Test for a restricted, damaged, leaking, or modified exhaust system from the catalytic converter forward.
  • Inspect for vacuum leaks at the intake manifold, the throttle body, and the injector O-rings.
  • Test the fuel injectors for improper operation.
  • Test for fuel contamination.
  • Test for excessive fuel in the crankcase due to leaking injectors.
  • Test the ignition system for improper operation.
Customer: replied 1 month ago.
This vehicle has 350,000 miles on it. It has been meticulously owned and maintained with a one owner, oil changes every 5000 miles. Any other recommendations based on the mileage?

How does vehicle run? Does it idle rough or lack power under hard acceleration?

Customer: replied 1 month ago.
It idles lightly rough like it has a misfire. It has plenty of power on the test drive. We hooked up our snap on scanner and did a cylinder contribution test and all of the cylinders look perfect with not one single misfire. We did find that the fuel cap will not click when we tighten it in the seal looks old so I'm pretty sure that is defective. Where should we head next?

These two codes are unrelated. First one the same thing I said would apply and 2nd code most likely means you have a vacuum leak if it idles rough but has good power while driving. Let me know if you have more questions, thanks.

Customer: replied 1 month ago.
Look at this sensor we found unplugged near the oil filter housing. Do you know what it is? Perhaps this is our cause ?
Customer: replied 1 month ago.

That looks like a pressure switch for AC which would be unrelated to problems.

Customer: replied 1 month ago.
Knock sensor ?????

Where exactly are we looking in the picture? Can you take another picture further away? Thanks.

Customer: replied 1 month ago.
Dan this picture is the sensor and the two lines that run right in front of the sensor are going to the oil cooler for the oil filter. We replaced the gas cap and plug in the center and have been testing the vehicle for a couple days now and we can't get the light to come back on however if you can help me look at my fuel trims on the scan tool to know what I'm looking for to identify a vacuum leak I would appreciate it

If fuel trim is good at idle but higher under hard acceleration this points toward restricted filter or fuel pump. If high at idle but good under hard acceleration this would point toward a vacuum leak. If high either way then mass airflow sensor or oxygen sensor. Let me know if you have more questions, please do not forget to rate answer, thanks.

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