P0161 Oxygen sensor heater circuit fault, bank 2 sensor 2

O2 sensor heater circuit malfunction (bank 2, sensor 2)

Monitor

A heater circuit fault on the sensor after the catalyst usually only affects emissions monitoring, so the car can normally be driven while you book a check.

It gets more serious if:

  • Inspect soon: Get it inspected soon if the engine runs rough or stalls, since other faults may be involved.

Source: how we rate severity

P0161 in short

P0161 means the heater circuit of the oxygen sensor after the catalytic converter on bank 2 has a fault. Causes are a failed sensor, a blown fuse, or wiring damage. It mostly affects emissions and the car is usually driveable, but fix it to pass inspection.

The post-catalyst oxygen sensor has a heater so it can work quickly after a cold start. P0161 is set when the computer sees a problem in that heater circuit on bank 2, sensor 2, per the standard code naming.

GM bulletin 3322 found incorrect sensors and harness causing heater codes including P0161 on 2004 trucks, Nissan has a flow chart for oxygen sensor codes, and Ford covers 2020 Super Duty and 2012 Expedition with the code.

Bank and sensor numbering comes from the maker, so check your service information.

Most likely causes

  1. Failed downstream oxygen sensor heater

    Common general cause
    Why it ranks here
    Reference pages list the sensor heater as the most common cause.
    What would change this
    Rises if the heater resistance is out of spec. Falls if it tests in spec.
    How to test the oxygen (o2) sensor

  2. Wiring, connector or fuse in the heater circuit

    Common general cause
    Why it ranks here
    Heater circuit faults are often a blown fuse or damaged wire.
    What would change this
    Rises if the fuse is blown or wiring is damaged. Falls if the circuit tests clean.

  3. Incorrect sensor or harness (GM 2004 trucks)

    Supported by vehicle data
    Why it ranks here
    GM bulletin 3322 names incorrect O2 sensors and wiring harness for these codes on 2004 trucks.
    What would change this
    Rises on the listed trucks. Falls on other vehicles.
    How to test the oxygen (o2) sensor

What to test first

Start at step 1. Each result tells you what it means and where to go next.

  1. Read all codes. Note P0141, P0135 and P0155 stored with P0161.

    Low riskTool: OBD-II scan tool

    • IfSeveral heater codes are stored

      It meansA shared fuse or power feed is likely.

      Go to step 2

    • IfP0161 alone

      It meansCheck the fuse and sensor.

      Go to step 2

  2. Check the oxygen sensor heater fuse and inspect the sensor connector and wiring.

    Low risk

  3. Have the sensor heater resistance and supply voltage tested.

    Best left to a shopTool: multimeter

    Warning:Exhaust components are hot and sensors can seize. Let a shop do it.

Symptoms

  • Check engine light
  • Failed emissions inspection
  • Usually no change in how the car drives

How to fix

  1. With the engine off, check the oxygen sensor heater fuse and connector.

Parts and cost context

  • Oxygen (O2) sensor:Confirm which sensor is bank 2 sensor 2 on your engine. Labour varies; get a quote.

Labor varies by vehicle and shop; get a quote before you approve a repair.

Compare used part prices on PartPriceGuide

On your vehicle

Ford

  • 2020 · F-250 Super Duty

    Supported by vehicle data

    Ford TSB 21-2090 covers 2020 Super Duty with P0161 among O2 heater codes. Not verified as current.

  • 2012 · Expedition

    Supported by vehicle data

    Ford TSB-13-5-7 covers the 2012 Expedition with heater codes. Not verified as current.

  • TSB 21-2090Status unverified

    MIL on with several O2 sensor heater codes including P0161

    2020f-250, f-350 · issued · NHTSA 10199477

    Covers 2020 Super Duty with 6.2L or 7.3L engines built before 5 June 2020 with the light and O2 sensor codes including P0161.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • TSB-13-5-7Status unverified

    MIL on with P0135, P0155 and possibly P0161

    2012expedition · issued · NHTSA 10052769

    Covers the light on with oxygen sensor heater codes on the 2012 Expedition and Navigator.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

Nissan

  • 2015 · Altima

    Supported by vehicle data

    Nissan NTB15051 points to a flow chart for O2 sensor codes including P0161 on 2015 models. Not verified as current.

  • NTB15051Status unverified

    Flow chart for oxygen sensor DTCs including P0161

    2015altima, murano, pathfinder · issued · NHTSA 10192579

    Directs technicians to a flow chart in the bulletin for several oxygen sensor codes including P0161.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

Chevrolet

  • 2004 · Tahoe

    Supported by vehicle data

    GM 3322 names incorrect O2 sensors and harness for heater codes on 2004 trucks. Not verified as current.

  • 3322Status unverified

    Incorrect O2 sensors and wiring harness causing heater circuit codes

    2004tahoe, silverado-1500, suburban · issued · NHTSA 10017196

    Covers incorrect oxygen sensors and a wiring harness causing heater circuit codes P0135, P0141, P0155 and P0161.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • P0141The heater in the downstream oxygen sensor on bank 1 isn't working as the computer expects

    Same system Supported by vehicle data

    GM and Ford bulletins list P0141 with P0161 for sensor heater circuit faults.

  • P0135The heater in the upstream oxygen sensor on bank 1 isn't working as the computer expects

    Same system Supported by vehicle data

    P0135 is the bank 1 sensor 1 heater code, listed with P0161 in GM bulletin 3322.

All Oxygen sensors codes

P0161 questions

Is P0161 the sensor before or after the catalytic converter?

After. Sensor 2 is downstream of the catalytic converter.

Sources and review

  1. Chevrolet 3322: Incorrect O2 sensors and wiring harness causing heater circuit codes — NHTSA manufacturer communications ,
  2. Nissan NTB15051: Flow chart for oxygen sensor DTCs including P0161 — NHTSA manufacturer communications ,
  3. P0161 trouble code explanation — TroubleCodes.net
  4. P0161 OBD-II trouble code — PartsAvatar
  5. Ford TSB-13-5-7: MIL on with P0135, P0155 and possibly P0161 — NHTSA manufacturer communications ,
  6. Ford TSB 21-2090: MIL on with several O2 sensor heater codes including P0161 — NHTSA manufacturer communications ,
Last reviewed
Written by
Saurabh K.
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