P0166 Code - O2 Sensor Circuit No Activity Detected Bank 2 Sensor 3
Quick Answer
The rear heated oxygen sensor (or sensor 3 for some vehicles), after three way catalyst (manifold), monitors the oxygen level in the exhaust gas on each bank. Common causes include Faulty Heated Oxygen Sensor Bank 2 Sensor 3, Heated Oxygen Sensor Bank 2 Sensor 3 harness is open or shorted, Heated Oxygen Sensor Bank 2 Sensor 3 circuit poor electrical connection. Severity is Moderate - service should be scheduled soon. The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.
- What it means
- P0166 indicates O2 Sensor Circuit No Activity Detected Bank 2 Sensor 3.
- Common causes
- Common causes include Faulty Heated Oxygen Sensor Bank 2 Sensor 3, Heated Oxygen Sensor Bank 2 Sensor 3 harness is open or shorted, Heated Oxygen Sensor Bank 2 Sensor 3 circuit poor electrical connection.
- Severity
- Moderate - service should be scheduled soon.
- Can I drive?
- The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.
Code P0166 Description
What are the Possible Causes of the DTC P0166?
- Faulty Heated Oxygen Sensor Bank 2 Sensor 3
- Heated Oxygen Sensor Bank 2 Sensor 3 harness is open or shorted
- Heated Oxygen Sensor Bank 2 Sensor 3 circuit poor electrical connection
How to Fix the DTC P0166?
Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.
What is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the P0166 code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.
Need more information about the P0166 code?
Need more information on how to fix the P0166 code? Get Access to Factory Service Manuals
Need Help with the Code?
Get the P0166 code diagnosed by a professional: Find a repair shop in your area
Information for Specific Makes
- P0166 Honda — Alternator B Terminal Circuit Low Voltage
- P0166 Mercedes-Benz — O2 Sensor Circuit No Activity Detected Bank 2 Sensor 3
Frequently Asked Questions about P0166 Code
1. What are the common symptoms of OBDII code P0166?
The common symptoms of P0166 include poor engine performance, decreased fuel efficiency, rough idling, and an illuminated check engine light.
2. What does OBDII code P0166 mean?
OBDII code P0166 indicates that there is no activity detected in the oxygen sensor circuit of Bank 2 Sensor 3 in the vehicle's exhaust system.
3. What are the possible causes of O2 Sensor Circuit No Activity Detected Bank 2 Sensor 3?
Possible causes of P0166 include a faulty oxygen sensor, damaged wiring or connectors, exhaust leaks, or issues with the vehicle's engine control module (ECM).
4. How can I diagnose the O2 Sensor Circuit No Activity Detected Bank 2 Sensor 3 issue?
Diagnosing P0166 typically involves checking the oxygen sensor's wiring and connectors, inspecting for exhaust leaks, testing the sensor's voltage output, and scanning the vehicle's ECM for related error codes.
5. Can I continue driving with OBDII code P0166?
It is not recommended to continue driving with code P0166 unresolved, as it can lead to further engine damage and reduced fuel efficiency. It is best to address the issue promptly.
6. How can I repair O2 Sensor Circuit No Activity Detected Bank 2 Sensor 3?
Repairing P0166 may involve replacing the faulty oxygen sensor, repairing damaged wiring or connectors, fixing any exhaust leaks, or reprogramming the ECM if necessary.
7. Is it possible to reset OBDII code P0166 without fixing the underlying issue?
While clearing the code can temporarily turn off the check engine light, the issue causing P0166 will persist unless properly diagnosed and repaired. It is best to address the root cause of the problem.
8. Can a DIY enthusiast fix OBDII code P0166?
Depending on the individual's skill level and access to tools, a DIY enthusiast may be able to address P0166 by replacing the oxygen sensor, checking wiring connections, or fixing minor exhaust leaks. However, more complex issues may require professional assistance.
9. How much does it cost to repair O2 Sensor Circuit No Activity Detected Bank 2 Sensor 3?
The cost of repairing P0166 can vary depending on the underlying cause, the vehicle's make and model, and labor rates. It is advisable to obtain quotes from reputable mechanics or automotive repair shops.
10. How often should I check the oxygen sensors in my vehicle to prevent OBDII code P0166?
It is recommended to include oxygen sensor inspections as part of regular vehicle maintenance, typically every 30,000 to 60,000 miles, to help prevent issues like P0166. Regular checks can help detect problems early and avoid more significant repairs.
Discuss the causes and fixes for P0166 OBDII Code
Code P0166 comments
No comments found for this page.
Fix Your Car Smarter
Try the New AutoCodes App!
Get complete OBDII diagnostics, repair solutions, and cost estimates, plus AI chat support on demand.
