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Ron Z.
Ron Z., - Honda Tech -
Category: Honda
Satisfied Customers: 17797
Experience:  18+yrs experience. State Inspector and Honda Diagnostics
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99 Accord 2.3 ULEV.Failed emission inspection with P1166.

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99 Accord 2.3 ULEV.
Failed emission inspection with P1166. They said code is "Manufacturer Controlled Fuel and Air Metering" and is related to the intake. On the internet all Honda P1166 codes I find seem to be O2 related: "HO2S Heater System Elect" or "Air/Fuel Ration Sensor Heater System". Which way do I go?

The P1166 is the code for a faulty heater in the Heated Oxygen Sensor (aka A/F Sensor). The oxygen sensor has a built in heater that the computer will command on to get the sensor to normal operating conditions within a matter of seconds when engine temp is cold. Replacing the Oxygen Sensor Bank1 Sensor1 should solve your problem. This sensor is located in the front of the engine:


Customer: replied 6 years ago.
Thanks, XXXXX XXXXX my research pointed to. Autozone wants $99 for a Bocsh sensor. Honda dealer $235 for a new one. I found a Denso OEM O2 sensor at for $53 (list price is $225). Any thoughts?
Actually, i've used the Bosch many times with excellent results. Obviously, the Honda dealer part is just outrageous and actually isn't that much different than the Bosch. The Denso i'm sure is just as good, however, i'm a big fan of buying parts from a person- this way if you get a defect, you have an actual person to go and deal with. My advise, buy the Bosch, get a good part, good price, and get the job done right the first time.
Customer: replied 6 years ago.
After I intall a new sensor and clear the code, as long as the code doesn't come back then the O2 sensor is working properly? How long do I need to wait to verify the problem is fixed? If the code comes back do I assume the new O2 sensor is faulty?
After the new sensor is in, and you clear the code, the usual "drive-cycle" for a Honda is roughly 50-75 miles of city/highway driving. (I'm an Inspector in Rhode Island, and I usually tell my customers to drive it a few days like normal). If the light stays off after that, you're golden. If it does come back, have the codes re-read, and if its the same code you may have a defect sensor. However, like i said- the Bosch have a very high success rate, you'll be fine. Think positive!
Customer: replied 6 years ago.
Can I clear the code myself without going back to garage?
Absolutely. While in the process of changing the Oxygen Sensor, remove the "NEG" cable from the battery. By the time you have replaced the sensor, and re-connect the "NEG" cable, that will clear the codes from the on board computer. Make sure you have a working key fob for your alarm system and a radio code, if equipped, as these systems sometimes reset as well with the "NEG" off.
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