Intermittent P1118
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From: SoMD
Intermittent P1118
For the last couple months I've been messing with a P1118 code. Started a few months ago when I noticed my fuel mileage was down 1-2MPG. Also sometimes a rough seeming idle (hard to tell with the diesel). Then it threw a P1118, so I replaced the temp sensor under the turbo. The code went away for a while then came back, fuel mileage didn't change. So I replaced the temp sensor in the air filter box. The code went away AND my fuel mileage seems to have come back to normal. Now, code thrown again. Ugghhh. Ideas? Search on P1118 hasn't been super useful. Seems like replacing the sensor under the turbo is the trick. Also seems to come up in combination with a bunch of other codes with battery problems. I suppose it's possible I have some sort of electrical gremlin. It throws the code on startup and stays on until I shut it off. Doesn't come on every time, is off more often than on.
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That's the Manifold Air Temperature (MAT).
The good thing about troubleshooting is that there are only two wires. One is a 5vR from the PCM and back to the Ground on the PCM. Easy to troubleshoot...
1. It is rare they fail, they just work.
2. The easy way to check this is to:
a. Run a KOEO, Delete the code.
b. Turn the Vehicle Off, then on, run a KOEO
c. Turn the Vehicle Off, if P1118 is present:
3. Check circuit integrity.
a. Jump Pin#1 and Pin#2
b. Turn the Vehicle Off, then on, run a KOEO,
Is P1118 is present? YES: you have an open in the Signal Wire REPAIR open in (SIG RTN) Circuit 359 (GY) between MAT sensor harness connector and the PCM.
c. If P1118 is not present, it's the AIT Sensor.
BTW: You can do this on any 5vR Circuit so long as its just supply / signal (two wires)
The good thing about troubleshooting is that there are only two wires. One is a 5vR from the PCM and back to the Ground on the PCM. Easy to troubleshoot...
1. It is rare they fail, they just work.
2. The easy way to check this is to:
a. Run a KOEO, Delete the code.
b. Turn the Vehicle Off, then on, run a KOEO
c. Turn the Vehicle Off, if P1118 is present:
3. Check circuit integrity.
a. Jump Pin#1 and Pin#2
b. Turn the Vehicle Off, then on, run a KOEO,
Is P1118 is present? YES: you have an open in the Signal Wire REPAIR open in (SIG RTN) Circuit 359 (GY) between MAT sensor harness connector and the PCM.
c. If P1118 is not present, it's the AIT Sensor.
BTW: You can do this on any 5vR Circuit so long as its just supply / signal (two wires)
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From: SoMD
If I clear the code and run a KOEO with sensor plugged in, no code.
If I remove the connector from the sensor and run KOEO, it throws a P1119.
If I jump the pins together and run KOEO, it throws a P1118.
From what I can tell, this means all is good as far as wiring goes?
Truck will run for several days without throwing a code. Today the light came on as I was driving down the road. Not during a KO sequence. Gas mileage is down 1-2 MPG.
If I remove the connector from the sensor and run KOEO, it throws a P1119.
If I jump the pins together and run KOEO, it throws a P1118.
From what I can tell, this means all is good as far as wiring goes?
Truck will run for several days without throwing a code. Today the light came on as I was driving down the road. Not during a KO sequence. Gas mileage is down 1-2 MPG.
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tmcalavy
1980 - 1986 Bullnose F100, F150 & Larger F-Series Trucks
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Jan 27, 2000 05:56 PM
