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edster 12-01-2013 12:15 AM

2003 GT High Idle after intake install
Hi all , I installed a Dorman intake manifold because my original one started leaking. any way i installed the new one and everything fine no leaks but now my idle around 2100 rmp and i cant figure it out. I got code P0113 - Open circuit in harness , Circuit High Input : Self-Test maximum. : circuit and PCM. which say i have a possible short short in the electrical wire harness. and that its putting out more voltage than maximum allowed which is 4.6v. so I checked it and its putting out 12v. Can a short cause it to shoot the wrong voltage? Anyway I went and bought a new Iac valve hoping that was the problem but it wasn't. Any suggestions?

red 2003 mustang gt with 4.6 motor

wmburns 12-01-2013 02:29 PM

Considering that the IAT sensor is on the +5 volt supply, the max voltage should be 5 volts. So 12 volts indicates a short to battery positive. If this were my car, I would be looking to see where the wiring harness could have been damaged during the repair.

IMO based upon the DTC code and the recent repair, replacing the IAC is a waste of $$.

P0113 - Intake Air Temperature (IAT) Circuit High Input

Indicates the sensor signal is greater than Self-Test maximum. The IAT sensor maximum is 4.6 volts or -50C (-58F).

Open circuit in harness
Sensor signal short to power
Damaged sensor
Improper harness connection
Damaged PCM

IAT V PID reading greater than 4.6 volts with key ON and engine OFF or during any engine operating mode indicates a hard fault.

edster 12-01-2013 09:44 PM

So could it be anywhere or should i trace the 2 wires going to the iac?

fordman777 12-01-2013 10:09 PM

Like he said look wherever you was messing with any wires or working around any. Start from the IAT Sensor which is INTAKE AIR TEMP SENSOR. Not IAC Idle Air Control Valve. Look at those wires and make sure it is plugged in and the wires are in good shape. If you don't know the IAT sensor is located right after the MAF plugged into your CAI.

edster 12-01-2013 10:24 PM

ok i'll check them thanks

edster 12-02-2013 04:24 PM

you guys were right i found a short in the right grey wire in the plug for the maf/iat had a short fixed it and now it runs good again thank you very much and have a great holiday

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