Engine-CodesHonda – P1166 Honda

P1166 Honda Code - Air/Fuel Ratio Sensor 1 Heater Circuit Malfunction

Quick Answer

The P1166 Honda code indicates a malfunction in the Air/Fuel Ratio Sensor 1 Heater Circuit. Common causes include Faulty Air/Fuel Ratio Sensor, Damaged wiring or connectors in the heater circuit, Engine Control Module malfunction. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means
P1166 Honda indicates Air/Fuel Ratio Sensor 1 Heater Circuit Malfunction.
Common causes
Common causes include Faulty Air/Fuel Ratio Sensor, Damaged wiring or connectors in the heater circuit, Engine Control Module malfunction.
Severity
High - diagnose this code as soon as possible.
Can I drive?
Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
Table of contents Created and updated by William Orellana on Sep 06, 2024
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Code P1166 Honda Description

The P1166 Honda code indicates a malfunction in the Air/Fuel Ratio Sensor 1 Heater Circuit. This sensor is responsible for measuring the oxygen content in the exhaust gases and sending that information to the engine control module to adjust the air/fuel mixture for optimal combustion. When the heater circuit within the sensor fails to operate correctly, it can lead to inaccurate readings and hinder the engine's performance.

OBDII Code P1166 Honda - Air/Fuel Ratio Sensor 1 Heater Circuit Malfunction
P1166 Honda Code - Air/Fuel Ratio Sensor 1 Heater Circuit Malfunction

Common Causes of P1166 Honda

  1. Faulty Air/Fuel Ratio Sensor
  2. Damaged wiring or connectors in the heater circuit
  3. Engine Control Module malfunction
  4. Issues with the heater circuit relay
  5. Exhaust leaks affecting sensor performance

Symptoms of P1166 Honda

  1. Check Engine Light illuminated on the dashboard
  2. Rough idling or stalling
  3. Decreased fuel efficiency
  4. Engine misfires
  5. Emissions exceeding legal limits

How to Fix P1166 Honda

  1. Diagnose the specific cause of the heater circuit malfunction using a diagnostic scan tool.
  2. Inspect the wiring and connectors for any damage or corrosion, repairing or replacing as necessary.
  3. Test the Air/Fuel Ratio Sensor for proper operation and replace if found to be faulty.
  4. Check the engine control module for any errors or malfunctions, resetting or replacing if needed.
  5. Clear the diagnostic trouble codes and test drive the vehicle to ensure the issue has been resolved.

Cost to Fix P1166 Honda

The cost of repairing a P1166 Honda code can vary depending on the specific cause of the issue and the labor rates in your area. On average, the repair for this type of problem can range from $200 to $500, including parts and labor. It's important to consult with a qualified mechanic or auto repair shop to get an accurate estimate based on your vehicle's make and model. Keep in mind that additional diagnostic time may be necessary to pinpoint the exact source of the problem.

Tech Notes for P1166 Honda





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When is the Code Detected?

If the element is not activated or the Engine Control Module (ECM) terminal voltage is a set value or less for at least a set time period when the power is drawn to the A/F sensor (sensor 1) heater, a malfunction is detected and the code is stored.

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Information for Specific Honda Models

About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P1166 Honda Code

No Frequently Asked Questions about P1166 Honda Code found.

Discuss the causes and fixes for P1166 Honda OBDII Code

  • to change the sensor with a new one, the error code of the computer and the board is removed?

  • What model and year is your Honda?

  • My vehicle idle is too high,and I have done so many things, still yet no results.

  • Besides the high idle, are there any more symptoms? what engine codes? what model and year is your Honda?

  • Just replaced upstream (A/F) oxygen sensor after getting code 1166 and the code will not go away.
    If there is a bigger scam than the Pennsylvania Emissions, I hope I never see it.

  • 1998 honda accord 2.3l has codes p1166 and p1167 I replaced both o2 sensors and the codes didn't go away so checked the fuses I found the one on the drivers side fuse box and it was good but when I tried to check the laf fuse on the passenger side fuse box it was empty and theres no wires

  • what is the manufacturer's part number

  • What model, year and engine size is your vehicle?