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Discussion Starter · #1 ·
hello all!
My '03 1.6liter elantra has a mystery for you guys.
It all starts with a check engine light, connected the OBD and there you have it: p0112 code for low voltage on the IAP sensor, checked a bit and it turns out that in this model the IAT and MAP sensors are the same sensor.
The following day the check engine light went off, and all was good for 2 weeks 'till the same check light went on with the same code. this has been going like that (on/off) the past few months with the affect being that the avg fuel consumption for HWY when the light is off is 12 KM/LITER and when it is on: 8 KM/LITER (25% worse).
I finally had the time to check if the sensor is the culprit, swapped the sensor with the exact same sensor of another same car model, put the other car's sensor into my engine and the check engine light is still on, put my sensor in the other car and start it and there is NO light! the sensor is good!!
I'm baffeled here, what is going on?
 

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Drives : Nissan NV200 Flies : Rans S6ES
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You need to know what the trouble code means in order to diagnose the fault that is causing it. P0112 doesn't mean a low voltage on the IAT sensor signal. It means the sensor signal is indicating too low a temperature, which actually means the signal voltage is too high.

The most likely cause of a temperature sensor signal voltage being too high is high resistance in the wiring, which could be caused by corroded terminals on the harness connectors or an intermittent break in the sensor signal wire. A high resistance on the sensor ground might cause the code too but I think that can be ruled out in this case because the IAT ground is shared with the MAP sensor. If the sensor ground was bad you'd likely have trouble code relating to the MAP or TPS logged as well as the IAT code.

Good luck tracing the fault.

Scottie.
 

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Discussion Starter · #3 ·
Update: one year ago i've cleaned the sensor's leads with contact cleaner.
Then, i've used electrical grease to mildly cover the leads.
The problem never showed since. So if anyone ever gets this code,try this first.
 

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Thanks for taking the time to confirm the fix. I'm sure the next guy will appreciate it.


Cheers.
 

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Kudos to AUTOSPARK, it seems his theory from a year ago of "high resistance" in the wiring was correct. Good call Scottie !!!
 
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