P0150 Oxygen sensor circuit fault on the bank 2 upstream sensor

O2 sensor circuit malfunction (bank 2, sensor 1)

Severity not verified — if the car runs badly, have it inspected

The sources describe P0150 as a sensor circuit fault with poor fuel economy and rough running, but none gives a drive-or-stop rating, so no class is claimed.

It gets more serious if:

  • Inspect soon: Get it inspected soon if the engine stalls, runs rough or loses power. A 2005 Hyundai Tucson owner reported the engine stopping while driving with P0150 stored; the dealer updated the engine software.

Source: how we rate severity

P0150 in short

P0150 means the computer sees a fault in the circuit of the front oxygen sensor on bank 2. A failed sensor, damaged wiring or an exhaust leak ahead of the sensor are the usual causes. Fuel economy and running quality can suffer, so have it checked soon rather than ignoring the light.

The front oxygen sensor on each bank should swing between a low and a high reading as the computer richens and leans the mixture. P0150 is the circuit fault for the sensor on bank 2, sensor 1, which is the one ahead of the catalytic converter. The computer sets it when that sensor voltage is outside what it expects.

A worn sensor is the common reason, but the sensor only reports what reaches it. Damaged or corroded wiring, a connector that has pulled loose, and an exhaust leak ahead of the sensor can all give the same code, and so can an engine that is running very rich or lean.

Some makers have found the cause in software. Kia has a bulletin that upgrades the engine computer for P0130 and P0150 on the 2005-2006 Optima and Sportage with the 2.7L engine, and one Hyundai Tucson owner reported a dealer fixing P0150 with a software update instead of a new sensor.

Most likely causes

  1. Worn or failed bank 2 front oxygen sensor

    Common general cause
    Why it ranks here
    TroubleCodes.net and Kelley Blue Book both list a defective or worn sensor first, and it is the part the code is named for.
    What would change this
    Rises if power and ground to the sensor are good but its voltage does not swing in closed loop. Falls if it switches normally.
    How to test the oxygen (o2) sensor

  2. Damaged, chafed or corroded sensor wiring or connector

    Common general cause
    Why it ranks here
    Both references list burnt, chafed, disconnected or corroded wiring and connectors, and the harness runs close to hot exhaust parts.
    What would change this
    Rises if the harness shows heat or rub damage or the connector is corroded. Falls if the wiring and connector are clean and secure.

  3. Exhaust leak ahead of the sensor

    Common general cause
    Why it ranks here
    Both references list an exhaust leak before sensor 1 as a cause, because outside air in the exhaust upsets the reading.
    What would change this
    Rises if you hear ticking at a cold start or see soot at a joint upstream of the sensor. Falls if the exhaust is tight.

  4. Engine computer software that needs an update (some models)

    Supported by vehicle data
    Why it ranks here
    Kia TSB-053 and TSB-075 cover an engine computer upgrade for P0150 on 2.7L Optima and Sportage, and a 2005 Tucson owner reported a software update at the dealer.
    What would change this
    Rises if a dealer finds your VIN covered by an update. Falls if the software is current or the vehicle is not listed.

  5. Engine running very rich or lean on that bank

    Possible — needs testing
    Why it ranks here
    TroubleCodes.net and KBB mention rich or lean conditions and vacuum leaks as things that can disturb the sensor signal; this is a weaker, indirect cause.
    What would change this
    Rises if fuel trim on bank 2 is far from zero or other mixture codes are stored. Falls if trims are normal.

What to test first

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

  1. Read all stored codes and the freeze frame data and note any other oxygen sensor or fuel trim codes stored with P0150.

    Low riskTool: OBD-II scan tool

  2. With the engine off and the exhaust cool, look over the sensor harness and connector for burns, rubbing, loose pins or corrosion.

    Use caution

    Warning:Exhaust parts stay hot for a long time after the engine stops. Let the exhaust cool fully before touching the harness near it.

  3. With a scan tool, watch the bank 2 sensor 1 voltage once the engine is warm and in closed loop, and have the exhaust checked for leaks ahead of the sensor.

    Best left to a shopTool: scan tool with live data

    Warning:Checking for exhaust leaks means working near a running engine and hot, carbon-monoxide-laden exhaust gas. Let a shop do it.

  4. Ask a dealer whether an engine computer update exists for P0150 on your VIN.

    Low risk

Symptoms

  • Check engine light on
  • Worse fuel economy
  • Rough running or hesitation
  • Black exhaust smoke in some cases
  • Engine stalls or loses power Gets more serious: stop and have it checked.

Compare with: Rough idle with the check engine light on

How to fix

  1. With the engine off and the exhaust cool, look over the visible wiring and connector at the front bank 2 oxygen sensor for damage, then ask a dealer whether an engine computer update applies to your VIN.

Parts and cost context

  • Oxygen (O2) sensor:Confirm which sensor is bank 2, sensor 1 on your engine before buying; a wiring fault or exhaust leak can mimic a bad 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

Kia

  • 2005–2006 · Sportage

    Supported by vehicle data

    Kia TSB-053 covers an engine computer software upgrade for P0130 and P0150 on 2.7L Sportage (and Optima). Whether it is still current is not verified.

  • TSB-053Status unverified

    ECM upgrade for DTC P0130 and P0150 (2.7L)

    2005–2006optima, sportage · issued · NHTSA 10033673

    Engine computer software upgrade for some 2005-2006 vehicles with the 2.7L engine that show a lit MIL with these codes.

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

Ford

  • 2009–2011 · E-150

    Supported by vehicle data

    Ford TSB 14-0022 provides a service procedure for P0130 or P0150 on 2009-2011 E-Series vans; the summary does not say what it is. Whether it is still current is not verified.

  • TSB-14-0022Status unverified

    DTC P0130 or P0150 with the MIL on

    2009–2011e-150, e-250 · issued · NHTSA 10055018

    A service procedure is provided for some E-Series vans. The NHTSA summary does not say what the procedure is.

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

No curated relationships for P0150 yet.

All Oxygen sensors codes

Sources and review

  1. P0150 trouble code page — TroubleCodes.net
  2. P0150 OBD-II code — Kelley Blue Book
  3. NHTSA complaint ODI 10405094 — NHTSA Office of Defects Investigation
  4. Kia TSB-053: ECM upgrade for DTC P0130 and P0150, 2.7L engine — Kia Motors America ,
  5. Ford TSB 14-0022: DTC P0130 or P0150 with MIL on — Ford Motor Company ,
  6. On-Board Diagnostic Trouble Codes (generic code title list) — Delaware Division of Motor Vehicles
  7. NHTSA complaint ODI 11278728 — NHTSA Office of Defects Investigation
Last reviewed
Written by
Saurabh K.
Editorial review
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Technician review
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