Hey everyone,
I am new to this forum and joined because I need some help. A few months ago I purchased a 2000 Honda Civic EX 4Spd Automatic off of craigslist and it has not stopped giving me problems. Currently I have two trouble codes: P0113 IAT sensor circuit high voltage, and P0172 Fuel system too rich bank 1. Also, the car idles very rough and very low and will stall out at unless I put it in neutral and rev the engine coming up to a stop.


So far I have replaced the following parts:

Primary O2 Sensor

IAT Sensor

Water pump

Spark plugs/wires

Distributor cap/rotor button

I have also recently cleaned out the throttlebody and ran a bottle of fuel injector cleaner through the engine.


Im stumped. Thanks in advance for any help.

Josh

 

Check if the IAT wires have been cut to install the infamous "ebay chip". If you find such a chip, remove it and restore the wiring to stock. You may need to pull a circuit diagram and test the IAT circuit all the way from the ECU pins to the sensor.

On some models the IAT sensor plug is the same type so it can get plugged into the canister purge solenoid and vice versa. That is not good.

Idling too low and stalling is usually a dirty IACV, but resolve the IAT situation first. Wrong readings from the IAT can cause a rich run.

 

There didnt appear to be and "ebay chip". I checked the wires with an Ohm Meter yesterday and they had very little resistance. Is this a good sign? Is there a better way to check for shorts?

Also, as far as the idle/stalling goes, could I possibly need a new PCV Valve? Would that cause these symptoms? Also, the IACV is not in the place it should be. I think instead it is mounted on the bottom of the throttle body but I have read that that is a FIT not and IAC. Is it possible I dont have an IACV and that is what is causing the problem?

Josh

 

Automatic has the IACV on the bottom of the throttle body. Certainly PCV valve should be checked but it's usually not a big factor in idling.

To test sensor wiring, disconnect battery, unplug ECU and measure sensor resistance from the ECU plug, it should be the same as measured at the sensor. Then unplug sensor too and measure resistance from wire to ground and other wires, should be infinite.

 

Oh ok I was kinda worried there. But thats good to know.

Ok, I couldn't find the ECU. Read that it was under the passenger side kick plate but don't know what screws go to what. Checked the resistance in ohms from one of the wires to the negative terminal on the battery and there was very little resistance.