Computer Codes
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Senior User
Joined: Apr 2002
Posts: 201
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From: Schaumburg, IL
Computer Codes
When the computer sets a code, how long does it store it? My check engine light came on about a month ago for about 10 minutes, then went out by itself. Hasn't gone back on since. I just got a notice from the state to take my van ('97 E150 with 5.4) for the annual emission test. One of the things they do is plug into the computer to check for codes. You flunk if they find any. I know I could disconnect the battery & make sure, but I'm wondering if this is necessary.
Thanks for all the great info on this forum. I find answers to questions I haven't even thought of yet.
Thanks for all the great info on this forum. I find answers to questions I haven't even thought of yet.
Hotshot
Joined: Aug 2002
Posts: 12,679
Likes: 15
From: BC, Canada
Computer Codes
This is out of the shop manual......
The OBD II system meets government regulations by monitoring the emission control system. When a system or component exceeds emission thresholds or a component operates outside of tolerance, a Diagnostic Trouble Code (DTC) will be stored and the Malfunction Indicator Lamp (MIL) will be illuminated.
The OBD II Monitors detect system faults and initiate DTC setting and MIL activation. Fault detection strategy and MIL operation are associated with drive cycles. A DTC is stored in the PCM keep alive random access memory when a fault is first detected. In most cases the MIL is turned on after two consecutive drive cycles with the fault. The DTC is cleared after 40 engine warm-up cycles without the fault being detected once the MIL is turned off. Once a Monitor turns on the MIL, it will require three consecutive drive cycles without a fault for the MIL to turn off. The operation of each of the OBD II Monitors is discussed in detail within this section.
Did you understand all that?
Pulling the battery cable off will clear the code but it will also set a code P1000 which means the truck's computer hasnt tested all the systems and that will cause it to fail the emissions test too
The OBD II system meets government regulations by monitoring the emission control system. When a system or component exceeds emission thresholds or a component operates outside of tolerance, a Diagnostic Trouble Code (DTC) will be stored and the Malfunction Indicator Lamp (MIL) will be illuminated.
The OBD II Monitors detect system faults and initiate DTC setting and MIL activation. Fault detection strategy and MIL operation are associated with drive cycles. A DTC is stored in the PCM keep alive random access memory when a fault is first detected. In most cases the MIL is turned on after two consecutive drive cycles with the fault. The DTC is cleared after 40 engine warm-up cycles without the fault being detected once the MIL is turned off. Once a Monitor turns on the MIL, it will require three consecutive drive cycles without a fault for the MIL to turn off. The operation of each of the OBD II Monitors is discussed in detail within this section.
Did you understand all that?
Pulling the battery cable off will clear the code but it will also set a code P1000 which means the truck's computer hasnt tested all the systems and that will cause it to fail the emissions test too
Thread Starter
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Senior User
Joined: Apr 2002
Posts: 201
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From: Schaumburg, IL
Computer Codes
thanks for the info, Dave. what if i pull the battery cables to clear the codes then drive the truck for a week or so before i go for my emissions test? that should give the computer time to run all tests - will it clear the p1000 code?
Hotshot
Joined: Aug 2002
Posts: 12,679
Likes: 15
From: BC, Canada
Computer Codes
Hi jse
I haven't heard of anyone that pulls codes for free but you might want to call around. Canuck Rubber maybe? NAPA?
I haven't heard of anyone that pulls codes for free but you might want to call around. Canuck Rubber maybe? NAPA?
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New User
Joined: Apr 2003
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From: Alberta Canada
Computer Codes
Thanks I will. The "check engine" light hasn't driven me crazy yet but it's pretty close.
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Joined: Jun 2003
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Computer Codes
Mine has been on for about five months this time. Everytime I take it in they say the EGR is clogged and needs replaced or the throttle body needs cleaned. After the last $400 fixing I said screw it. Truck is still running fine, every now and then I feel a little roughness. What the hell, it has 125,000 on it.
If anyone has any other ideas let me know.
If anyone has any other ideas let me know.
More Turbo
Joined: Oct 2001
Posts: 539
Likes: 1
From: San Mateo, CA
Computer Codes
Hey Myke,
If you are going to disconnect the battery then go to autozone to make sure the computer cleared, why not just go to autozone and have them read the computer(if it's still in there). Then you might have a heads up on a potential future problem.
It's my understanding that reading the codes also clears them. Can anyone confirm this?
If you are going to disconnect the battery then go to autozone to make sure the computer cleared, why not just go to autozone and have them read the computer(if it's still in there). Then you might have a heads up on a potential future problem.
It's my understanding that reading the codes also clears them. Can anyone confirm this?
New User
Joined: Sep 2002
Posts: 20
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From: Miami USA
Computer Codes
from Harbor Freight - it works just fine. When I read the codes with it, it turned off the light and reset the the code to "no codes". I needed to drive 3 cycles to get the light to come back on again, at which time I could check it and clear it again.
I was amazed that it worked, but it helped diagnose my problem (spark plug coil) so I could fix it myself.
Dave
I was amazed that it worked, but it helped diagnose my problem (spark plug coil) so I could fix it myself.
Dave
New User
Joined: Jun 2003
Posts: 4
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From: Winchester, Illinois
Computer Codes
My "Check Engine" light has been coming on for a few days then goes out. The truck was also running a little rough at times. I replaced the EGR valve and that fixed it. For a while. The it started over again. This time when you gave it the gas from a stop it shook real bad getting going. I took it to Autozone and checked the codes. "Catalyst Effeciency below Threshold". They said I needed to replace the catalytic converters. WELL! I'm sure you guys know what those cost!! I was looking at $1268 from Ford and could not find any direct fit aftermarkets. The muffler shop inspected the cats and said that they seemed ok so I took it back by Autozone to recheck the codes. They told me the same thing again. I needed cats. I took it to Ford and put it on the computer. They said that the number 3 sparkplug and wire were bad and that this may be giving the code that it was. I almost spent a ton of money on something that I had a lifetime warranty on!
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