Service Engine light
Thread Starter
Teching In
Joined: Mar 2004
Posts: 12
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Service Engine light I just finished a Hooker LT header and ORY pipe install with a little
help from you guys ,thanks. Now the service engine light is
on and the fans come on right away. Any idea what the problem is ?
help from you guys ,thanks. Now the service engine light is
on and the fans come on right away. Any idea what the problem is ?
Well with so little info to go on it could be anything from EGR, AIR codes to any number of misfire codes to a couple of oxygen sensor codes(slow switching,etc.) get it scanned and post again. 
Thread Starter
Teching In
Joined: Mar 2004
Posts: 12
Likes: 0
car was fine before I started, put on LT, ORY . Hooked front 02
sensors back up with extentions and used 02 sems for back.
started the car yesterday was fine, no S.E. light but fans were coming on.
started car after hooking up exhaust and S.E. light was on.
sensors back up with extentions and used 02 sems for back.
started the car yesterday was fine, no S.E. light but fans were coming on.
started car after hooking up exhaust and S.E. light was on.
From experience if a MIL (service engine soon) light comes on RIGHT away there is a dead short(unconnected Sensor/broken sensor) you will see the same thing if you clear the light with a scan tool and it returns right away, check the obvious, the fans coming on is most likely a computer limp mode in action, good luck, Ken
if the fans are on im willing to bet some money u shorted out the wire on the dirver side head for the coolant temp sensor, check that bad boy out, does your coolant gauge work?
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Staging Lane
Joined: Apr 2004
Posts: 71
Likes: 0
I had the same thing with mine. I bought a new sensor and that cured
the fan coming on, but I'm still showing the P0118 code. I think it must
be a wire somewhere, but can not find it. Last night I checked the plug
on the sensor and tried to move the main harness from the PCM that runs
down near the passenger side header away from the header.
I let it idle for 1/2 hour, no codes! This morning I'm going for a ride to see
if it's still acting up. I posted a question on it in the PCM section, and am
waiting to see if any others have the same troubles.
the fan coming on, but I'm still showing the P0118 code. I think it must
be a wire somewhere, but can not find it. Last night I checked the plug
on the sensor and tried to move the main harness from the PCM that runs
down near the passenger side header away from the header.
I let it idle for 1/2 hour, no codes! This morning I'm going for a ride to see
if it's still acting up. I posted a question on it in the PCM section, and am
waiting to see if any others have the same troubles.
Thread Starter
Teching In
Joined: Mar 2004
Posts: 12
Likes: 0
Forgot to plug sensor back in after putting headers
on.Temp. gauge is working now. Last toy was a 64 GTO
did not have all the emissions stuff on it ,alot easier to work
on. If this was the only problem I had will the SES light go
out or does it need to be reset ? Will the light reset if I undo
the battery cable ?
thanks for all your help
on.Temp. gauge is working now. Last toy was a 64 GTO
did not have all the emissions stuff on it ,alot easier to work
on. If this was the only problem I had will the SES light go
out or does it need to be reset ? Will the light reset if I undo
the battery cable ?
thanks for all your help
Staging Lane
Joined: Apr 2004
Posts: 71
Likes: 0
the code is for the Coolant Temp. Sensor. You can undo the battery
cable for a few minutes or pull the fuse for the PCM under the hood with
the ignition on, and the car not running. Shut off the ignition then replace
the fuse. That should reset everything. Your PCM with have to relearn
but that only takes a few miles of driving and some time idling with the
a/c on and the a/c off.
Glad everything is o.k. for you. Be sure the headers do not touch the
02 sensor wires. Plenty of high heat insulation tape is a good idea on
those wires.
cable for a few minutes or pull the fuse for the PCM under the hood with
the ignition on, and the car not running. Shut off the ignition then replace
the fuse. That should reset everything. Your PCM with have to relearn
but that only takes a few miles of driving and some time idling with the
a/c on and the a/c off.
Glad everything is o.k. for you. Be sure the headers do not touch the
02 sensor wires. Plenty of high heat insulation tape is a good idea on
those wires.
yeah u can undo the terminals and it may reset it, sometimes it doesnt. but like he said pull the fuse and that iwll do it for sure. but if u start it up and drive for a little itll eventually go off, within a few miles or so or a few start ups
i think this is the first time i was able to really help someone out and know what the problem was once i first read the post! haha with good info it makes it real easy to nail the problem
I have been struggling with O2 codes ever since the install of LT's. These sensors are not cheap, thus it is not practical to keep changing them everytime they decide to throw a code. It is so frustrating. 
Staging Lane
Joined: Apr 2004
Posts: 71
Likes: 0
Please don't say you're changing them after they throw a code. Buy
yourself an ODB2 reader. You can see what code is thrown and clear it.
I just went for a ride. It threw the 02 codes as I left my block. I cleared it
then drove for over 1 hour with no more codes. I have an appointment
for a Dyno tune, till then I'll just keep an eye on things with my scanning
tool.
yourself an ODB2 reader. You can see what code is thrown and clear it.
I just went for a ride. It threw the 02 codes as I left my block. I cleared it
then drove for over 1 hour with no more codes. I have an appointment
for a Dyno tune, till then I'll just keep an eye on things with my scanning
tool.
after headers u will throw a heater code dont worry about it. just fails start up test when the car is cold cause the sensors dont get hot enough being relocated farther down on the header.
Originally Posted by Hawkeye2
Please don't say you're changing them after they throw a code. Buy
yourself an ODB2 reader. You can see what code is thrown and clear it.
I just went for a ride. It threw the 02 codes as I left my block. I cleared it
then drove for over 1 hour with no more codes. I have an appointment
for a Dyno tune, till then I'll just keep an eye on things with my scanning
tool.
yourself an ODB2 reader. You can see what code is thrown and clear it.
I just went for a ride. It threw the 02 codes as I left my block. I cleared it
then drove for over 1 hour with no more codes. I have an appointment
for a Dyno tune, till then I'll just keep an eye on things with my scanning
tool.