ajpats26

Hello,
I am hoping to get someone's guidance on troubleshooting P0113 - IAT sensor high volt Fault Code in my Honda Civic 05 LX. I searched through a few threads and did not come across an answer, and so posting a new thread.

My first step was taking out the IAT sensor and checking for resistance. Resistance is changing with changing temperature (I used hair dryer to blow hot air) and so I am presuming sensor is working good.

My next troubleshooting step is verifying voltage on IAT pinconnector.to check if wiring harness is okay.
Using a voltmeter, how can I validate the sensor wire harness is working as needed?
Should I be seeing 5V on both pin connectors? If I see 5V in one and 0V in other, does that mean the harness itself is bad?

Thank you for reading and thank you in advance for your help.

ezone

Do you know what caused the code to set? (maybe someone just unplugged the sensor while the key was on)

Erase code. Then see if the code returns. If it returns right away, you know the problem is still present and active.
If it does not recode right away, drive it until it does set a code.

Assuming it sets the code right away, a decent scanner or app that can show live sensor data is gonna be extremely useful right now. Does that sensor show a temperature that's accurate?

Voltage checks....sensor unplugged, one wire must be ground, the other may show 5 volts.

ajpats26

Thanks for your response.
Yeah, I believe the sensor was taken out with key ignition on... which may explain the fault code.

I actually unplugged the car battery for a few minutes to reset the code, but the code showed up again... and so assuming the fault hasn't cleared.

I unplugged the IAT sensor and using a voltmeter, I measured 5 V on one pin and 0 V on the other (with the other prong of voltmeter grounded)
Is that how it should be?

ezone

So it should erase and stay gone, if you clear (erase) memory.....and battery disconnect is supposed to erase engine codes (but I don't know if there's a specific time needed to do so....maybe try disconnect for 15 minutes? )


What's the code number? (Pxxxx format please)
If you have a code reader, can't it erase codes? If no code reader, how are you getting the fault code?


Yes 5v and 0v, but on the 0v wire you need to flip your meter to ohms (if selectable use the lowest range 0-200 ohms) and make sure it shows close to zero ohms


No bent pins in the sensor where the wires connect?

ajpats26

Fault code is P0113. I don't own a fault code reader, but stopped by Autozone and the gentleman was kind enough to gave me a print out of the code. (probably need to buy one)

Thanks for the advice. I'll try re-measuring tomorrow morning and flip my meter to ohms. Will also check for bent pins

Appreciate your guidance.

ezone

You can buy a bluetooth dongle and a phone app (might be cheaper than a code reader), several people have said it's darn useful
Google 'torque pro'

Colin42

Super useful dongle is like $20 and the app is $5

ajpats26

So I remeasured this morning.
Voltage on the two pins are 5V and 0V as expected

However, on the pin showing 0V, the resistance (with 0-200 setting) is fluctuating around 35 ohms. Sometimes shoots upto 190 ohms for a split second, but that may be human error.

Any ideas what might be causing that?

ezone

35 sounds reasonable imo and human error sounds reasonable too if you aren't making positive contact with the terminal

Have you erased codes, then see if it returns right away?

ajpats26

I tried erasing codes by disconnecting battery for several minutes. I think the erase was successful because when I turned on the ignition, CEL disappeared for a few seconds.

Unfortunately it came back with the code.

Ah well, I'll get it diagnosed at the professional shop. I don't know I am qualified enough for further troubleshooting to be honest

Thanks again for all your help and patience

ezone

thought of another check......you have code P0113...... iat voltage high

Bridge the terminals in the connector with a paper clip----that should cause code P0112 (iat voltage low)...that would prove wiring is ok and computer recognizes both open and short circuit conditions, that would pretty much leave only a bad temp sensor'

but you should have a code reader handy if you try this

ajpats26

Cool. Thanks.

Let me buy the dongle that you recommended, will give it a try & respond.

ezone

Once you have that and the app, you'll probably be able to display a live data list of sensor inputs and read exactly what the engine computer "sees" as the temperature input for that sensor (it is supposed to be a believable temperature at all times)

Open circuit/disconnected/voltage high condition, the temp value will likely read -40 degrees on the data display......
With the connector terminals shorted together, the temp value may read something like 300F or higher