Guide To P0166 OBD Error Code Solutions

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Oftentimes, Engine Warning Light turns up almost immediately it senses the OBD code error. This directly impacts the engine performance as it struggles with power and acceleration as well as failed fuel system causing increased consumption of fuel by the engine.

An oxygen sensor for a particular engine bank that is not responding at all, causes the PCM to store a trouble code and possibly illuminate the service engine soon light.

Oxygen sensors play an important role in the fuel, ignition timing, and valve timing strategies calculated by the PCM. The PCM collects information from various sensors around the engine to calculate the most suitable fuel/air ratio, ignition timing setting, as well as VVT/VCS settings to ensure that the engine delivers the optimal power with the best fuel economy.

If the PCM detects that it takes longer than about 60 seconds or so for the sensor element to heat up, or that the signal voltage does not move outside of the 390 to 490 millivolt range, it will deem the oxygen sensor to be inactive, set code P0166, and trigger the Check Engine Light.

What causes the problem of O2 Sensor Circuit No Activity Detected (B2 S3)?

• Damaged or Faulty heated oxygen sensor
• Electrical connector at the oxygen sensor can be damaged or disconnected
• Faulty or shorted wiring in the oxygen sensor circuit
• Connection error with sensors due to blown fuses
• Exponential variance in the fuel pressure
• Excessive exhaust leaks and vacuum leaks on the engine
• Damaged catalytic converter due to debris accumulation
• Faulty ECU (Engine Control Unit) picking up wrong data

1. Heated Oxygen Sensor - The fault in the oxygen sensor leads to failure of the fuel delivery system, and engine control module. Replace faulty sensors immediately.
2. Engine Control Module - Faulty ECM may flash and store wrong OBD error and cause engine stalling and hard idles. Thus, replace faulty ECM immediately.
3. Powertrain Control Module - P0166 error code also relates to problems with the PCM. This can cause improper engine and throttle response. Replace faulty PCM now.
4. Catalytic Converter - Catalytic converters at fault will lead to dropped fuel efficiency and performance along with increased emissions. Thus, replace faulty parts now!
5. Diagnostic Tool - Use professional scanning and diagnostic tools to detect the OBD error code. Buy from us now!
6. Mass Air Flow Sensor - Faulty MAF will be unable to read voltage fluctuation efficiently, thus indicating the PCM about its faults and flashing the OBD code P0166. Thus, replace it immediately.
7. Exhaust Gas Temperature Sensor - It is important to measure the temperature of the gas emitted out form the combustion chamber to know about the oxygen levels and manage the functioning of catalytic converters and the fuel delivery system. Thus, replace if found faulty.
8. Fuel Pump - Right amount of fuel mixed with air is necessary to maximise engine output and reduced emissions form the exhaust. Thus, check for any damages and replace, if necessary.
9. Manifold Absolute Pressure Sensor - Damaged MAP sensor can cause rough engine idles and loss of acceleration and hesitation while driving. Buy new MAP sensor now!

Common Symptoms

• Significant decrease in the fuel economy
• Engine stalling and not starting along with loss of power and response
• Rough idle and hard starting of the engine
• Carbon deposit build up impacting the spark plugs
• Malfunction Indicator Lamp (MIL) illuminated

Replace the following components to correct the OBD code P0166 if they are found faulty. But it’s important to do a proper inspection before doing such replacement.

• Oxygen sensor replacement
• Faulty fuel pump replacement
• Damaged wirings and connectors replacement
• Faulty PCM replacement

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It is very important to use the correct tools to diagnose a problem with a very professional outlook. Each and every default component needs to be examined as the ECM sensor comes into play. Follow the following step by step analysis to do the diagnosis of error code P0166.

• Use a professional grade Diagnostic scan tool to check for all codes present (must be used to show live sensor data).
• Observe and take note of any freeze frame data that is associated with the code along with the current collected data after the test drive.
• After the confirmation of P0166, clear the code and perform a test drive under the same circumstances shown in the freeze frame data.
• If the P0166 code returns, visual inspection is performed to check the integrity of the wiring and sensor.
• Scan with a tool used to monitor live data from Bank 2 Sensor 3 if the previous step is found to be okay.
• Check and test the ECM if the sensor checks out as under the rarest of chances it may be possible that ECM is faulty and needs replacement.

Common Mistakes When Diagnosing OBD Code P0166

Never directly assume the Heated Oxygen Sensor is bad and needs replacement. The test procedure must be followed at all times to ensure that the wiring and other components are in good condition. Most of these problems are related to wiring touching the exhaust system. Always seek professional help to get the diagnosis as there might be many occasions where the diagnosis is much cheaper than perceived.