Engine-CodesAcura – P1166 Acura

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

Quick Answer

The P1166 diagnostic trouble code for Acura vehicles indicates a malfunction in the Air/Fuel Ratio Sensor 1 Heater Circuit. Common causes include Faulty Air/Fuel Ratio Sensor 1, Damaged wiring or connectors in the heater circuit, Malfunctioning Engine Control Module (ECM). 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 Acura indicates Air/Fuel Ratio Sensor 1 Heater Circuit Malfunction.
Common causes
Common causes include Faulty Air/Fuel Ratio Sensor 1, Damaged wiring or connectors in the heater circuit, Malfunctioning Engine Control Module (ECM).
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 10, 2024
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Code P1166 Acura Description

The P1166 diagnostic trouble code for Acura vehicles indicates a malfunction in the Air/Fuel Ratio Sensor 1 Heater Circuit. This sensor is responsible for monitoring the oxygen content in the exhaust gases and sending this information to the engine control module (ECM) to adjust the air-fuel mixture for optimal combustion. The heater circuit in the sensor helps it reach operating temperature quickly, allowing for accurate readings.

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

Common Causes of P1166 Acura

  1. Faulty Air/Fuel Ratio Sensor 1
  2. Damaged wiring or connectors in the heater circuit
  3. Malfunctioning Engine Control Module (ECM)
  4. Corrosion or contamination in the sensor or circuit
  5. Electrical issues such as blown fuses or relays

Symptoms of P1166 Acura

  1. Decreased fuel efficiency
  2. Rough idling or engine misfires
  3. Hesitation or lack of acceleration
  4. Check Engine Light illuminated on the dashboard

How to Fix P1166 Acura

  1. Use an OBD-II scanner to confirm the P1166 code and pinpoint the issue.
  2. Inspect the wiring and connectors in the heater circuit for damage or corrosion.
  3. Test the Air/Fuel Ratio Sensor 1 for proper operation and replace if necessary.
  4. Check the ECM for any fault codes or malfunctions and address them accordingly.
  5. Clear the code and perform a test drive to ensure the issue is resolved.

Cost to Fix P1166 Acura

The typical repair costs for addressing a P1166 code can range from $200 to $500, depending on the specific cause of the issue and the cost of parts and labor. It is important to note that diagnosis time and labor rates can vary between auto repair shops, so it is advisable to obtain quotes from multiple sources before proceeding with the repair. Additionally, the cost may be higher if the ECM needs to be replaced or if there are other underlying issues contributing to the code.

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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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.

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