I take air temp sensor

[Ted Wilusz]

96 Honda Civic dx 1.6. Got used Ecu and installed. Numbers matched old Ecu. Took for test drive and now I get a code for iat circuit range/performance. Noticed with old Ecu and newly installed Ecu the iat reading on scanner is reading 370 weather it is cold or at operating temp. Been reading about the iat but not understanding why old Ecu never picked up that code. And also what a normal evading for this should be. By reading it says that it should be inline with the coolant temp. Coolant temp is 196 degrees. But iat reads 370. Is this reading in degrees? That is where I am lost. My code reader is sorta old but still works. It’s a actron cp9575. This car has an aftermarket cold air intake on it. Air filter is clean. Don’t see any problems with connection to iat. Looked at the plug on harness it seems ok. No bad fuses. Could it also be shorted wire with that constant reading? Thank in advance for any help. Also will this keep my car in readiness cycle for o2 and cat monitors?

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[Mike]

[quote=”twilusz” post=189369]96 Honda Civic dx 1.6. Got used Ecu and installed. Numbers matched old Ecu. Took for test drive and now I get a code for iat circuit range/performance. Noticed with old Ecu and newly installed Ecu the iat reading on scanner is reading 370 weather it is cold or at operating temp. Been reading about the iat but not understanding why old Ecu never picked up that code. And also what a normal evading for this should be. By reading it says that it should be inline with the coolant temp. Coolant temp is 196 degrees. But iat reads 370. Is this reading in degrees? That is where I am lost. My code reader is sorta old but still works. It’s a actron cp9575. This car has an aftermarket cold air intake on it. Air filter is clean. Don’t see any problems with connection to iat. Looked at the plug on harness it seems ok. No bad fuses. Could it also be shorted wire with that constant reading? Thank in advance for any help. Also will this keep my car in readiness cycle for o2 and cat monitors?[/quote]

IAT should read within + /- 10 degrees of the outside air temperature with the key on, engine off on a cold engine.
This walks you through testing a similar IAT sensor for shorts, open circuit and bad sensor.
http://troubleshootmyvehicle.com/honda/2.2L-2.3L/how-to-test-code-P0113-page-1
Yes, a bad sensor will keep some or all emissions tests from running, as it is keeping the system in open loop..
http://troubleshootmyvehicle.com/honda/2.2L-2.3L/how-to-test-code-P0113-page-1

[Ted Wilusz]

Thank you for the link for testing. I will follow it and let you know what I find. The pending code is P0111. The scan tool shows the it is reading 370 degrees all the time. My old ecu never had any pending codes. But it still had reading of 370 degrees. Runs good. No missing. Just could not get out of readiness for O2 and cat monitors. I did find that my old ecu # 37820-p2e-a01, new ecu 37820-p2e-a02. Called Honda was told that it was a newer ecu but still compatible. Using ohm meter sensor reading open 1600 and continues to climb. Tried to test for open wire. Red lead on red wire with yellow tracer and black lead to ground. No voltage. Checked for contenutity red lead in other wire and black lead to ground no contenutity. Didn’t try jumping wire yet. Remember my reading is 370 even when it is unplugged. Think shortly in wiring harness. Question I have is to check ecu to see if wire is bad. Should the key be on engine off. Red lead to back side of connector to ECU and black to ground. Is that correct? Got another iat and using ohm meter it is at 1600. Shouldn’t it be lower than that? But I will follow your link and check everything. Thank you for your time. Will keep everyone up to date with testing. All help is appreciated very much. Can you tell me is the wire for it in d connector for ecu. Noticed I have 2 wires with same color. Which pin should I be checking?

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