i have a 1996 honda accord ex with a 2.2L vtec. My check engine light has been on for some time and i desperately need to have my car inspected --- i have a OEM II code reader and the only code that comes up is p0112. i have taken apart the intake, checked the air filter and replaced the IAT sensor, however the code will not go away even if i use the scan tool to 'erase' codes. i tried disconnecting the battery overnight and when i got in the car and turned the key to the 'on' position the code was on immediately. has anyone else had this problem or can anyone please point me in a new direction? the car runs great and has no other issues that prevent it from driving like a dream. i'm at my wits end here! Thanks in advance.

 

The IAT sensor is on the back of the manifold towards the firewall. I just want to make sure you replaced the right part.

It may be the wiring too. Here is a brief outline of the tests.

Measure the resistance across the two pins of the new IAT sensor. It should be within 0.4 and 4 Kohms. If not, then you got a bad IAT sensor out of the box. Also, turn the key to the II position, and measure the voltage between the red/yel wire and body ground. It should have 5V.

Let us know what you find.

You can also download a 94 shop manual from the online manuals thread in the DIY section. I posted a spooner link that has that file. I only gave you the first part of the instructions that start on page 11-49. Depending on what you find, you can follow the diagnostic tree to figure out what is wrong.

 

thank you. i'll post the results.

 

I did the test and was able to verify that the new IAT sensor is working, however the voltage from the 14 pin connector to the sensor is a full 12 volts so the tip of the sensor is melting again. I assume I'll have to pull a full wiring diagram to try and find the part/parts which should be converting the 12v to 5v?

 

I think the ECU supplies the 5V to the IAT sensor.

I am not sure which 14-pin connector you are talking about to test for voltage.

What voltage do you read between the red/yel wire on the IAT sensor plug and body ground with the key in the II position?

 

The wire is yellow, and it registers the full 12v when grounded. So from there I was able to trace the wiring back to a large 14 pin unit to the right of the engine compartment/towards the windshield more if that makes sense. I tested the pins to check which wire connected to the IAT sensor, but I am unable to tell where that connection comes from before that main hub of wiring. Do you know what could cause the voltage to be so high? With the p0112 code telling me the IAT sensor temp is too high, and the sensor tip melting, I assume the extra voltage is the main problem. Where to go from there... I'm at a loss.

 

I should clarify. By "right side" I mean drivers side. There are two multi pin connectors.

 

Large multi-pin connectors near the shock-tower?

Maybe it's not the same wire? Check voltage in the wire at the IAT itself. Should be the ECU itself that sends 5v to the sensors, not some separate "device" out in the circuitry of the car.

 

Yes. Near the shock tower is correct. Sorry... I'm not the most mechanically inclined. My father has been helping me with my trouble shooting. We checked the continuity of the sensor wires and both the black and yellow wires were registering the full 12v, which definitely seemed strange. We then ran the lines back to the 14 pin connector and checked the continuity and made sure we were running the same lines back and the voltage is constant at 12v so if the ecu is what regulates the voltage, thats my next step.

 

I am having the same issue (P0112 code, 12V at the sensor). Was there any resolution to this?