Tighten Gas Cap and Check Engine Lights
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Joined: Mar 2013
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Tighten Gas Cap and Check Engine Lights
Wanted to share my recent experience.
2008 Impala SS started surging slightly at cruising speeds. I cleaned the MAF sensor. Nothing changed. The next day I get a message on the dash to Tighten Gas Cap. It wasn't loose. That afternoon the Check Engine light appeared. I double checked to make sure my hoses were reconnected properly to the air intake tube. Check. I then discovered that my remote starter (from the factory) was no longer working. Hmmm. I took it to my local Auto Zone and got the diagnostic codes of P0455 and P0121. I then took the intake hose back off the throttle body housing and sprayed TB cleaner in there while wiping out what I could with a rag. I fired up the engine (after some extra cranks to clean the cleaner out of the intake), cruised two miles down the road and the check engine light disappeared, no more message to tighten gas cap, no more surging, and the remote starter now works. Unbelievable.
I think my K&N affects this more than a paper filter would. I suspect the oils from the filter cause faster buildup on the sensing elements of the intake.
2008 Impala SS started surging slightly at cruising speeds. I cleaned the MAF sensor. Nothing changed. The next day I get a message on the dash to Tighten Gas Cap. It wasn't loose. That afternoon the Check Engine light appeared. I double checked to make sure my hoses were reconnected properly to the air intake tube. Check. I then discovered that my remote starter (from the factory) was no longer working. Hmmm. I took it to my local Auto Zone and got the diagnostic codes of P0455 and P0121. I then took the intake hose back off the throttle body housing and sprayed TB cleaner in there while wiping out what I could with a rag. I fired up the engine (after some extra cranks to clean the cleaner out of the intake), cruised two miles down the road and the check engine light disappeared, no more message to tighten gas cap, no more surging, and the remote starter now works. Unbelievable.
I think my K&N affects this more than a paper filter would. I suspect the oils from the filter cause faster buildup on the sensing elements of the intake.
Senior Member
True Car Nut
Joined: Dec 2009
Posts: 9,616
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From: western,ny state
ive got a k&n on my 07 monte(same) and havent had any issues. you just got to be careful with the oil. in fact ive put them on every car and havent had any issues. FYI the gm remote start wont work with any cel no matter if its unsafe or not.
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Joined: Mar 2013
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I didn't know that. Good info. Thanks.
Thread Starter
Junior Member
Joined: Mar 2013
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I need to add info here. I just got another CEL for P0455. I had already cleaned out the TB. So, I looked closer and noticed a line port missing a tube going into the intake just after the MAF sensor. I capped it off and drove for 50 miles and the CEL is gone. Now I just need to locate where the tube went to and reconnect. Anybody have any diagrams?
