P0157 The oxygen sensor after the catalytic converter on bank 2 (sensor 2) is sending a signal voltage that is too low

O2 sensor circuit low voltage, bank 2 sensor 2

Monitor

An oxygen sensor circuit fault mostly affects emissions and fuel economy, and TroubleCodes.net reports little or no drivability change, so book a repair rather than stopping.

Source: how we rate severity

P0157 in short

P0157 means the signal voltage from the downstream oxygen sensor on bank 2, the side without cylinder 1, is lower than the sensor can produce. A failed sensor, damaged or corroded wiring, or an exhaust leak ahead of it are the usual causes. Drivability is normally unchanged, so book a repair.

Oxygen sensors produce a voltage that moves with the oxygen in the exhaust. P0157 sets when bank 2 sensor 2 reports a voltage below its possible range.

TroubleCodes.net says sensors typically last under five years because of heat and exhaust exposure, and notes water in connectors and exhaust leaks between the catalytic converter and sensor as causes.

Bank 2 is the side of the engine that does not have cylinder 1.

Most likely causes

These are general causes for this code across vehicles. None is specific to one make or model.

  1. Failed downstream oxygen sensor

    Common general cause
    Why it ranks here
    TroubleCodes.net lists sensor failure first among the causes.
    What would change this
    Stuck or out-of-range live readings compared with the other sensors raise it.
    How to test the oxygen (o2) sensor

  2. Damaged harness or corroded connector

    Common general cause
    Why it ranks here
    TroubleCodes.net lists harness damage from impact or debris and water corrosion in connectors.
    What would change this
    Visible damage or water in the connector raises it.

  3. Exhaust leak between the catalytic converter and sensor

    Possible — needs testing
    Why it ranks here
    TroubleCodes.net lists an exhaust leak between the converter and the sensor.
    What would change this
    A sooty or audible leak near the sensor raises it.
    How to test the catalytic converter

What to test first

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

  1. Read all codes and freeze-frame data and note any fuel trim, misfire, exhaust or other oxygen sensor codes stored with P0157

    Low riskTool: OBD-II scan tool

    • IfFuel trim, misfire or other sensor codes are also stored

      It meansRepair those first; they can disturb this sensor.

      Go to step 2

    • IfP0157 is the only code

      It meansInspect the sensor wiring next.

      Go to step 2

  2. With the exhaust cold, inspect the sensor wiring, connector and related fuses for damage, corrosion and routing near hot parts

    Use cautionTool: visual inspection

    Warning:Let the exhaust cool fully before touching the sensor or its wiring. Back-probe connectors gently, never pierce insulation, and follow the wiring diagram for your engine.

  3. Unplug the sensor and test its resistance and the circuit continuity, voltage and ground against the specification for your engine

    Best left to a shopTool: digital multimeter; wiring diagram

    Warning:Let the exhaust cool fully before touching the sensor or its wiring. Back-probe connectors gently, never pierce insulation, and follow the wiring diagram for your engine.

Symptoms

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

How to fix

  1. With the exhaust cold, inspect the sensor harness and connector for damage or water, and look for exhaust leaks near the sensor.

Parts and cost context

  • Oxygen (O2) sensor:Use the correct sensor for that bank and position on your engine; sensors in different positions are often different parts.

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

Compare used part prices on PartPriceGuide

On your vehicle

Jeep

  • 2015 · Wrangler

    Supported by vehicle data

    Jeep bulletin 05149171A asks for a contact to be called before replacing the left downstream (2/2) O2 sensor on a 3.6L JK because of a P0157 fault code. Whether it is still current is not verified.

  • 05149171A$Status unverified

    Jeep bulletin: contact before replacing O2 sensors for P0131 or P0157

    2015compass, wrangler · issued · NHTSA 10140214

    Jeep bulletin 05149171A for the 2015 Compass and Wrangler. The summary asks that a named contact be called before replacing the left downstream (2/2) O2 sensor on a 3.6L JK because of a P0157 fault code, and gives a similar instruction for the upstream sensor on a 2.4L MK with P0131. Only the NHTSA summary was read, not the full bulletin; the summary does not give the repair.

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

Ford

  • 2015 · F-150

    Supported by vehicle data

    Ford bulletin 15-0072 covers 3.5L EcoBoost engines built before 4/14/2015 with the MIL on and one or more codes including P0157. Whether it is still current is not verified.

  • 15-0072Status unverified

    Ford bulletin: 3.5L EcoBoost MIL with one or more codes including P0157

    2015f-150 · issued · NHTSA 10058058

    Ford bulletin 15-0072 for the 2015 F-150. The summary says certain 3.5L EcoBoost engines built before 4/14/2015 may have the MIL on with one or more codes, including P0157 (alongside P0060, P0161, P0054, P0137 and P0141). Only the NHTSA summary was read, not the full bulletin; the summary does not give the repair.

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

Dodge

  • 2004 · Durango

    Supported by vehicle data

    Dodge bulletin 1802904 covers driveability improvements for MIL illumination with codes including P0157. Whether it is still current is not verified.

  • 1802904Status unverified

    Dodge bulletin: driveability improvements for MIL codes including P0157

    2004durango · issued · NHTSA 10008053

    Dodge bulletin 1802904 for the 2004 Durango. The summary lists driveability improvements for MIL illumination with codes P0137, P0157, P0403, P0404, P0405, P0406, P2174 and P2175. Only the NHTSA summary was read, not the full bulletin; the summary does not give the repair.

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

Cadillac

  • 2004 · CTS

    Supported by vehicle data

    Cadillac bulletin 01585 is titled post O2 water intrusion and lists P0157 among its codes. Whether it is still current is not verified.

  • 01585Status unverified

    Cadillac bulletin: post-catalyst O2 sensor water intrusion codes including P0157

    2004cts · issued · NHTSA 10005425

    Cadillac bulletin 01585 for the 2004 CTS. The summary is titled post O2 water intrusion and lists P0137, P0138, P0140, P0141, P0157, P0158, P0160, P0161, P2232 and P2235, and refers to SIT bulletin 1413806. Only the NHTSA summary was read, not the full bulletin; the summary does not give the repair.

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

No curated relationships for P0157 yet.

All Oxygen sensors codes

Sources and review

  1. P0157 trouble code page — TroubleCodes.net
  2. On-Board Diagnostic Trouble Codes (generic code title list) — Delaware Division of Motor Vehicles
  3. 05149171A$: Jeep bulletin: contact before replacing O2 sensors for P0131 or P0157 — Jeep
  4. 15-0072: Ford bulletin: 3.5L EcoBoost MIL with one or more codes including P0157 — Ford
  5. 1802904: Dodge bulletin: driveability improvements for MIL codes including P0157 — Dodge
  6. 01585: Cadillac bulletin: post-catalyst O2 sensor water intrusion codes including P0157 — Cadillac
Last reviewed
Written by
Saurabh K.
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