Check Engine Light
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Junior Member
Joined: Dec 2004
Posts: 1
Likes: 0
From: McKinney Texas
Check Engine Light
Need some help with the check engine light on my early 97 4.6L supercab flareside F150. The light seems to come on when the gas tank is about half empty and it usually goes away shortly after filling up. i use medioun grade gas and the issue is intermittent. I have paid the dealership twice to fix it and they keep changing O2 sensors but it only lasts 6 months and it's at it again. I have no way of knowing the code. Is there an obvious or known issue with this particular model truck and the check engine light? I'll apreciate the feedback. Thanks in advance. Ralph...
Senior Member
Joined: Mar 2003
Posts: 102
Likes: 0
From: Somewhere in Wisconsin(for now)
Look for a loose vacuum line. When I had my remanufactured engine installed the dealership forgot to reconnect a vacuum line. In my case it was located on the firewall to the left of the master cylinder. In laymans terms, when the gas tank is over half - 3/4 full their is no monitoring for vacuum in the gas tank. Somewhere in that half to 3/4 full range the computer starts to monitor vacuum in the gas tank. If a hose is loose there is no vacuum and the CEL goes on. Similar to having a bad gas cap causing the CEL to go on. Sorry but I forgot the code that comes up with this.
Senior Member
Joined: Oct 2002
Posts: 7,295
Likes: 125
From: St. Louis (Out in the woods)
Of course you can find out the code.
Many auto parts stores will scan it for free.
Without the code(s), you will get only guesses which will likely be wrong.
The grade of gas is irrelevent.
The computer does not receive any input from the fuel level sender, so it never knows how much fuel is in the tank. OBDII monitors for the evaporative emissions system use other parameters to determine when to execute.
It all boils down to "You need the code(s)" in order to get any useful advice.
Steve
Many auto parts stores will scan it for free.
Without the code(s), you will get only guesses which will likely be wrong.
The grade of gas is irrelevent.
The computer does not receive any input from the fuel level sender, so it never knows how much fuel is in the tank. OBDII monitors for the evaporative emissions system use other parameters to determine when to execute.
It all boils down to "You need the code(s)" in order to get any useful advice.
Steve
Senior Member
Joined: Mar 2003
Posts: 102
Likes: 0
From: Somewhere in Wisconsin(for now)
Yes. Do get the code.
I looked up the ODBII code I got and it was emissions related.
P1455 Evap. Emission Control Sys. Leak Detected (Gross Leak/No Flow).
In my case it ended up being a vacuum line that wasn't connected. The description of the fuel level I make came from the Ford tech. I'm just relaying my experience here hoping I can help someone out.
I looked up the ODBII code I got and it was emissions related.
P1455 Evap. Emission Control Sys. Leak Detected (Gross Leak/No Flow).
In my case it ended up being a vacuum line that wasn't connected. The description of the fuel level I make came from the Ford tech. I'm just relaying my experience here hoping I can help someone out.