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P0147 Code – What Does It Mean & How To Fix It

This is one of the most frequent OBD2 trouble codes. Read the full article below to know what it means, how to fix it, and what other codes may show related to it.


The DTC code is an alphanumeric designation used for a vehicle’s OBDD system to identify specific problems within individual components. P0147 contains a DTC for the O2 sensor circuit that runs from Bank 1, Sensor 3, which is referred to as a downstream O2 sensor. These sensors play an important role in controlling the oxygen content of exhaust gases, once they are injected into a catalytic converter.


A problem with the down voltage of Bank 1’s O2 sensor is shown in P0147. In particular, it is observed that the voltage output is not in line with the anticipated range. Different factors that affect the ability of a sensor to read accurately may be responsible for this discrepancy.


  • Defective Oxygen Sensor: One of the main root causes of the P0147 code is a deficient downstream O2 sensor. Voltage measurements can become erroneous as a result of dirty or worn-out sensors.
  • Wire Problems: Corroded or damaged connections and wires connected to the downstream O2 sensor might obstruct the signal’s transfer, lowering voltage readings.
  • Exhaust System Leaks: Leaks in the exhaust system that is close to the O2 sensor’s downstream location might cause spurious air to enter the system, which can distort voltage readings.
  • Issues with the catalytic converter: A faulty catalytic converter might result in erroneous readings in the downstream O2 sensor, setting off the code.


  • Check Engine Light Illumination: The Check Engine Light illumination on the dashboard of the car is the P0147 code’s most obvious symptom.
  • Lower Fuel economy: A faulty O2 sensor might result in incorrect fuel mixture regulation, which lowers fuel economy.
  • Engine Performance Problems: Due to erroneous sensor readings, the vehicle’s engine may have poor acceleration, rough idling, or trouble starting.


The P0147 code has to be identified using a methodical process:

  • OBD-II Scanner: To recover the stored DTCs from the vehicle’s Engine Control Module (ECM), a mechanic will utilize an OBD-II scanner.
  • Visual Inspection: The technician will visually check the exhaust system, the downstream O2 sensor, and its wiring for any obvious blemishes or problems.
  • Sensor Testing: Using specialized equipment, it will be tested to see how the downstream O2 sensor responds and outputs voltage under varied exhaust situations.
  • Cross-checking: To confirm the issue, compare the downstream O2 sensor values to the specifications and the upstream sensor readings.

Common mistakes

  • To replace the O2 sensor without checking its root cause, as other factors such as wiring issues or leakages in the exhaust pipe may have contributed to this code. 
  • Insufficient attention was paid to checking the codes of associated problems, which could provide further insight into this issue.

How serious is this?

While the P0147 code is not capable of causing immediate or serious problems for drivability, it should not be disregarded. If not addressed, disruption of the downstream O2 sensor could lead to an increase in emissions, lower fuel efficiency, and potential damage to a catalyst converter.

What repairs can fix the code?

repair manuals

  • O2 Sensor Replacement: If the downstream O2 sensor is shown to be defective, the problem can be fixed by swapping it out with a brand-new, high-quality sensor.
  • Repairing wire or connections: Correct signal transmission can be achieved by addressing any corroded, damaged, or attached wire and connections.
  • Repairing Exhaust Leaks: The O2 sensor can give correct voltage measurements if any leaks in the exhaust system are fixed.

Related codes

  • P0146: O2 Sensor Circuit Signal Stuck Lean (Bank 1, Sensor 3)
  • P0148: O2 Sensor Circuit High Voltage (Bank 1, Sensor 3)


A potential problem with the downstream O2 Sensor on Bank 1 is indicated in the P0147 DTC code, specifically indicating a low voltage output. Vehicle owners and mechanics are empowered to act without delay when they understand the meaning, causes, or symptoms of this code. Optimized engine performance, fuel consumption, and emissions control are ensured by addressing the problem through proper diagnosis and repair. 

If you come across the P01 code or suspect any O2 47 sensor-related problem, it will be helpful for you to seek assistance from qualified technicians so that your driving experience can be simplified and more effective.

P0147 Code – What Does It Mean & How To Fix It