P015B Front oxygen sensor slow to respond, lean to rich (bank 1, sensor 1)

O2 sensor delayed response lean to rich, bank 1 sensor 1

Monitor

TroubleCodes.net lists the check engine light, poorer fuel economy and reduced performance, so the car is usually drivable while you arrange a check.

It gets more serious if:

  • Inspect soon: Inspect soon if a reduced engine power message shows or the car jerks or hesitates. GM bulletin PIP-5402 names a reduced engine power message with this code, and a Cruze owner reported shuddering.

Source: how we rate severity

P015B in short

P015B means the front oxygen sensor on bank 1 reacts too slowly when the exhaust changes from lean to rich. A worn sensor, damaged wiring, an exhaust leak or a failing catalytic converter can cause it. The car usually drives normally, but get it checked soon, especially with a reduced power message.

The front oxygen sensor tells the computer how rich or lean the exhaust is. When the mixture is made richer on purpose, the sensor should swing quickly. If it swings too slowly, the computer sets P015B.

TroubleCodes.net lists a worn sensor, burnt or disconnected wiring, a failing catalytic converter and exhaust leaks, and says to fix misfire and air-flow codes first.

GM has a series of bulletins (PIP-5402) for the check engine light or reduced power with this code on 2013 to 2018 Malibu, Regal, ATS, CTS and similar cars, and a separate bulletin on the 2016 to 2017 Cruze. Subaru has issued engine computer reprogramming for P015A/P015B.

Most likely causes

  1. Front oxygen (air-fuel) sensor worn or slow

    Common general cause
    Why it ranks here
    TroubleCodes.net lists a defective sensor first.
    What would change this
    Rises if wiring and exhaust test good and the sensor reads slowly. Falls if a leak or wiring fault is found.
    How to test the oxygen (o2) sensor

  2. Exhaust or intake leak near the sensor

    Supported by vehicle data
    Why it ranks here
    TroubleCodes.net lists exhaust leaks, and GM bulletin PIP5633 names a possible intake manifold or exhaust leak with P015B on 2019 Silverado and Sierra 1500.
    What would change this
    Rises if a leak is heard or found at the manifold or joints. Falls if the exhaust and intake are tight.

  3. Burnt, broken or disconnected wiring or connector

    Common general cause
    Why it ranks here
    TroubleCodes.net lists wiring and says to check harnesses near hot exhaust parts.
    What would change this
    Rises if a harness is melted or a connector loose. Falls if wiring tests good.

  4. Engine computer software needs an update

    Supported by vehicle data
    Why it ranks here
    Subaru bulletin 09-78-21 supplies engine computer reprogramming files for P015A and/or P015B, and GM bulletin 17-NA-155 covers the code on the 2016 to 2017 Cruze. Both summaries are unverified.
    What would change this
    Rises on a covered model with the update not installed. Falls otherwise.
    How to test the engine control module (ecm / pcm)

  5. Failing catalytic converter

    Possible — needs testing
    Why it ranks here
    TroubleCodes.net lists the converter as a possible cause, but it is a weaker fit than the sensor.
    What would change this
    Rises if exhaust and sensor test good and catalyst codes are present. Falls otherwise.
    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; note any lean code (P0171), misfire, air-flow or throttle codes.

    Low riskTool: OBD-II scan tool

    • IfMisfire, lean or air-flow codes are also stored

      It meansDiagnose those first, as TroubleCodes.net advises.

      Go to step 2

    • IfP015B is alone

      It meansInspect the sensor wiring and exhaust.

      Go to step 2

  2. With the engine cool, inspect the sensor wiring and connector, and the exhaust and intake for leaks.

    Use caution

    Warning:The exhaust is hot after driving. Let it cool fully first.

  3. Ask a dealer whether a bulletin or software update applies to your model, and watch the sensor with a scan tool.

    Best left to a shopTool: scan tool with live data

    Warning:Needs a professional shop with the right scan tool and wiring diagrams; do not guess at this step.

Symptoms

  • Check engine light on
  • Slightly poorer fuel economy
  • Reduced engine power message or jerking in some reports Gets more serious: stop and have it checked.

How to fix

  1. With the engine cool, look for a loose oxygen sensor plug and listen for an exhaust leak at the manifold when starting the engine.

Parts and cost context

  • Oxygen (O2) sensor:Check for leaks and software updates before buying a sensor. Labor 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

Chevrolet

  • 2013–2016 · Malibu

    Supported by vehicle data

    GM communication PIP-5402 gives diagnosis for P015B or a reduced engine power message on the Malibu. Whether it is still current is not verified.

  • 2012–2017 · Cruze

    Possible — needs testing

    GM bulletin 17-NA-155 covers P015B on 2016 to 2017 Cruze. A 2012 Cruze owner had P015B with P0171 and shuddering; that car was not repaired.

  • PIP-5402Status unverified

    Check engine light with P015B or reduced engine power message

    2013–2016malibu · NHTSA 10078885

    GM preliminary information with diagnosis and repair steps; revised several times (A to E). NHTSA summary only.

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

  • 17-NA-155Status unverified

    MIL illuminated with P015B set

    2016–2017cruze · NHTSA 10190265

    GM bulletin for the 2016 to 2017 Cruze; the NHTSA summary names an engine control module cause.

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

Subaru

  • 2015–2018 · Forester

    Supported by vehicle data

    Subaru bulletin 09-78-21 supplies ECM reprogramming for P015A/P015B on Forester and WRX.

  • 09-78-21Status unverified

    ECM reprogramming for P015A and/or P015B

    2015–2019forester, wrx · NHTSA 10199934

    Subaru reprogramming files; NHTSA summary only.

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

  • P0171Engine computer has reached its limit adding fuel on bank 1: the mixture is lean

    Shares causes Possible — needs testing

    A Cruze dealer readout and GM bulletin context pair P015B with P0171 (bank 1 too lean).

All Oxygen sensors codes

P015B questions

Can I drive with P015B?

Usually yes, but get it checked soon. Reduced power or shuddering means sooner.

Sources and review

  1. P015B O2 sensor delayed response, lean to rich (bank 1 sensor 1) — TroubleCodes.net
  2. General Motors bulletin PIP-5402: check engine light with P015B or a reduced engine power message — General Motors
  3. NHTSA complaint ODI 11182030, 2012 Chevrolet Cruze: dealer read P015B (O2 sensor delayed response) with P0171 after the car jerked and shuddered — NHTSA
  4. General Motors bulletin PIP5633: check engine lamp with P015B stored, possible intake manifold or exhaust leak, 2019 Silverado/Sierra 1500 — General Motors
  5. Subaru bulletin 09-78-21: ECM reprogramming files to correct P015A and/or P015B — Subaru
  6. General Motors bulletin 17-NA-155: MIL with P015B set on 2016-2017 Cruze — General Motors
Last reviewed
Written by
Saurabh K.
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