IAT Sensor Problem

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Panopticon31
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Joined: Wed Aug 17, 2016 2:28 pm
Car: 1998 240sx Kouki

IAT Sensor Problem

Postby Panopticon31 » Thu Jun 15, 2017 12:30 pm

Currently trying to get a 1998 S14 registered but am failing emissions due to it throwing two codes, one for the knock sensor and one for the IAT sensor (P0110 code).
The IAT is obviously unhooked but neither I or the shop can find where its supposed to plug into. There is a spare plug near the sensor but the plugs dont match.
Hoping someone can look at the pictures and point my in the right direction.
Also if the harness doesnt match for whatever reason , is there a way i can force clear the codes and force the emissions monitors into a ready state so i can pass the OBD-II test? Thanks.


http://imgur.com/a/yGBTI


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centralcoaster33
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Car: 240SX #5-1997
Location: Central Coast, CA

Re: IAT Sensor Problem

Postby centralcoaster33 » Thu Jun 15, 2017 1:32 pm

You can clear codes, but you can't force monitor tests. The knock sensor is a PITA to get at, but it can be done. There are threads here with instruction for extensions and u-joints to get at it without taking off the intake. There is also a chance that you have just a bad wire in the harness or harness extension (from intake area to the actual Knock Sensor). So, check those plugs and put some dielectric grease in them. If code persists and you're not up to replacing the sensor, they you'll need a bit of luck and timing. First clear all codes and drive some of the drive cycles to get the monitors up and passing. I think knock sensor will come near last, so you want to stop the driving and have the SMOG test done before that gets triggered. This may take you some trial and error.

Intake air temp sensor near the MAF sensor plugs into the wire harness coming from the front of the valve cover area. The plug in your photo does not look like mine (1995 s14). Wait, I see two plugs (just noticed the other photos also). So, the one with the orange insulation is not the AIT plug. The other one is and is what should be matched up.

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Panopticon31
Posts: 13
Joined: Wed Aug 17, 2016 2:28 pm
Car: 1998 240sx Kouki

Re: IAT Sensor Problem

Postby Panopticon31 » Thu Jun 15, 2017 2:10 pm

Yeah I understand the orange plug is NOT the IAT connector on the harness. But is literally the ONLY plug visible in that vicinity of the engine bay that is open.

Also I read about the knock sensor and know its a pain in the a**. But at least its straight forward, whereas the IAT is a mystery as to what the hell its supposed to plug into.

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centralcoaster33
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Joined: Tue Apr 05, 2005 10:41 am
Car: 240SX #5-1997
Location: Central Coast, CA

Re: IAT Sensor Problem

Postby centralcoaster33 » Thu Jun 15, 2017 4:24 pm

The IAT will plug into the engine harness. The harness goes along the injectors, turns and crosses the front cover, then should have like four plugs coming from there. Two for the distributor, one MAF and one IAT. Perhaps your's is re-wrapped to hide cut wires, but that's where they belong. Perhaps someone has put the wrong plug type onto your wires. You can test the plug to ECU pins for continuity. The wiring details would be part of the FSM, EC chapter, under the P0110 code.


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