Engine-Codes - Mercedes-Benz - P0161 Mercedes-Benz

P0161 Mercedes-Benz Code - HO2S Heater Performance Bank 2 Sensor 2

- Code Popularity: 18,462 Views
- Repair Importance Level: 2/3
- Repair Difficulty Level: 2/3
Table of contents
ChatAC AutoCodes.com AI Chat

What are the Possible Causes of the DTC P0161 Mercedes-Benz?

NOTE: The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.
  • Faulty Rear Heated Oxygen Sensor Bank 2
  • Rear Heated Oxygen Sensor Bank 2 harness is open or shorted
  • Rear Heated Oxygen Sensor Bank 2 circuit poor electrical connection
  • Inappropriate fuel pressure
  • Faulty fuel injectors
  • Intake air leaks
  • Exhaust gas leaks

Code Tech Notes

Replacing the Rear Heated Oxygen Sensor Bank 2 usually takes care of the problem

⚠ Does your Mercedes-Benz have Safety Recalls? → Check here

How to Fix the DTC P0161 Mercedes-Benz?

Check the 'Possible Causes' listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.

Search for P0161 Mercedes-Benz Questions and Answers: Search here →

What is the Cost to Diagnose the Code?

Labor: 1.0

The cost to diagnose the P0161 Mercedes-Benz code is 1.0 hour of labor. The diagnosis time and labor rates at auto repair shops vary depending on the location, make and model of the vehicle, and even the engine type. Most auto repair shops charge between $75 and $150 per hour.

When is the Code Detected?

The Powertrain Control Module (PCM) runs the heater test only on a cold start (depends on the cumulative air flow) and only once an ignition cycle. When you start the engine the PCM monitors the HO2S voltage. When the HO2S voltage goes above or below the bias range threshold, the PCM determines how much time it took. If the PCM detects that the process took too much time for the HO2S to enter into normal operating range, the P0161 code will set. The time the process takes the HO2S to reach operating temperature is based on the amount of air that flows into the engine.

What are Code Possible Symptoms?

  • Engine Light ON (or Service Engine Soon Warning Light)
  • Higher fuel consumption

What Does the P0161 Mercedes-Benz Code Mean?

The Powertrain Control Module (PCM) supplies a bias voltage (approximately 450 mV) on the Heated Oxygen Sensor (HO2S) signal high and low circuits. When you turn the ignition to the ON position, battery voltage is supplied to the HO2S heater. As the heater reaches the operating temperature, the HO2S voltage responds by changing from a bias voltage range to the normal operation. Typically, as the HO2S reaches the operating temperature, the HO2S voltage goes from a bias voltage to a voltage below 300 mV. Depending on the exhaust gas content, it is possible for the HO2S voltage to go above 450 mV.

P0161 Mercedes-Benz Code - HO2S Heater Performance Bank 2 Sensor 2

Need more Information on the Code?

Need more information on how to fix the P0161 Mercedes-Benz code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P0161 Mercedes-Benz code diagnosed by a professional: Find a repair shop in your area