P0036 A fault in the heater control circuit of the downstream oxygen sensor on bank 1

HO2S heater control circuit, bank 1 sensor 2

Monitor

The heater only helps the downstream sensor warm up, and the only sign Troublecodes.net lists is the check engine light. It will fail an emissions test, and Kelley Blue Book says not to drive long with it set, so book a repair.

It gets more serious if:

  • Stop: Stop if the check engine light starts flashing: that means an active misfire hot enough to damage the catalytic converter. Pull over where nothing flammable is under the car and let it cool.
  • Inspect soon: Have it looked at soon if the engine loses power or goes into reduced-power mode. Kelley Blue Book lists reduced performance and failsafe mode, and owner complaints pair P0036 with a car that would not accelerate.

Source: how we rate severity

P0036 in short

P0036 means the engine computer found a fault in the heater circuit of the downstream (after the catalytic converter) oxygen sensor on bank 1. Wiring or connector damage, a failed heater inside the sensor, or a lost power or ground feed are the usual causes. The car normally drives as before, but get it repaired soon.

An oxygen sensor only reads correctly once it is hot, so each one has a small electric heater that the engine computer switches on after a cold start. The computer watches that heater circuit, and P0036 is stored when the circuit on the bank 1 downstream sensor does not behave as expected. Sensor 2 is the sensor after the catalytic converter; bank 1 is the side of the engine with cylinder 1, and an inline engine has only bank 1.

The code covers the wiring as well as the sensor. TroubleCodes.net lists wiring faults on the power side or the ground side of the circuit, and a heater element with high resistance or an open circuit. Kelley Blue Book adds a corroded exhaust ground strap. Because the sensor sits under the car, connectors and harness there take heat, water and road debris, and carmaker bulletins for this code repeatedly point at connectors and wiring rather than the sensor.

The downstream sensor mainly checks how well the catalytic converter works, so a dead heater rarely changes how the car drives. The cost is that the monitor may not run and the check engine light stays on, which fails an emissions test. Some makers define the code differently on some engines: Nissan's bulletin for 2016-2017 Altima and Pathfinder says to follow the bank 2 air-fuel sensor heater procedure for P0036, so use the service information for your exact engine.

Most likely causes

  1. Damaged, corroded or chafed wiring or connector at the sensor circuit

    Supported by vehicle data
    Why it ranks here
    Most vehicle bulletins for this code name wiring, not the sensor: Ford's 2021-2022 Bronco Sport and 2022 Maverick bulletins describe corrosion or water in connectors, GM's 2013-2015 Enclave, Traverse and Acadia bulletin describes wires chafed on an A/C hose coupling, and FCA's 2010-2012 Ram bulletin replaces the oxygen sensor connectors. Only summaries were read and none is verified current.
    What would change this
    Corrosion or water in a connector, rubbed insulation, a wire touching metal, or a fault that changes when the harness is moved raises it. Clean, dry connectors and an intact harness lower it.

  2. Failed heater element inside the downstream oxygen sensor

    Common general cause
    Why it ranks here
    Both TroubleCodes.net and Kelley Blue Book list a faulty sensor or a heater with high resistance or an open circuit. It ranks after wiring because bulletins keep finding wiring first, and one owner complaint (11767161) describes a downstream sensor replaced without clearing the code.
    What would change this
    A heater that measures open or outside the engine's resistance specification, with good wiring and supply, raises it. A good heater reading lowers it.
    How to test the oxygen (o2) sensor

  3. Corroded or broken exhaust ground strap

    Common general cause
    Why it ranks here
    Kelley Blue Book lists a corroded exhaust system ground strap as a cause; a poor ground shows up as a ground-side circuit fault.
    What would change this
    Visible corrosion or a loose strap, or voltage drop across the ground path, raises it. A solid ground lowers it.

  4. Lost power feed from a fuse or the powertrain relay

    Supported by vehicle data
    Why it ranks here
    GM's 2013-2015 bulletin notes an open Emission 1 fuse with P0036 and several other O2 heater codes, and GM's 2006 H3 bulletin sends the technician to the powertrain relay when P0036 is stored with P0030, P0135 and P0141. A supply fault usually sets several heater codes together. Summaries only.
    What would change this
    Several O2 heater codes stored at once, or a blown emissions fuse, raises it. A code on this sensor alone lowers it.
    How to test the underhood fuse block (engine compartment fuse box)

  5. Engine computer fault or software

    Possible — needs testing
    Why it ranks here
    Ford has a bulletin for 2016-2018 Edge with the 2.0L EcoBoost that names P0036 stored in the computer, and one owner (complaint 11767161) says the dealer replaced the downstream sensor and updated the software, yet the light returned. The summary does not say what the bulletin changes, so this is weak evidence.
    What would change this
    Raised only after wiring, supply and the sensor have tested good. A dealer can check whether a bulletin applies to the vehicle.
    How to test the engine control module (ecm / pcm)

What to test first

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

  1. Read all stored and pending codes and note whether other oxygen sensor heater codes or a Fuse or relay concern appear alongside P0036.

    Low riskTool: OBD-II scan tool

    • IfSeveral O2 heater codes are stored together, such as P0030, P0031 or P0037

      It meansA shared power feed is the likelier fault.

      Go to step 3

    • IfP0036 is stored alone or with P0138 (downstream sensor circuit)

      It meansInspect this sensor's wiring and connector first.

      Go to step 2

  2. With the exhaust fully cold, follow the downstream sensor's wiring from the sensor to its connector and look for melted or rubbed insulation, wires touching the exhaust or an A/C line, and a corroded or wet connector. Check the exhaust ground strap.

    Use cautionTool: visual inspection, flashlight

    Warning:Exhaust parts stay hot enough to burn long after the engine stops, so let the car cool for at least an hour. Never work under a car supported only by a jack.

  3. With the ignition off, unplug the sensor and measure heater resistance across the heater terminals against your engine's specification. Then, with the key on, check that the heater supply and ground at the harness side are present, using the wiring diagram. Check the fuse and relay your manual lists for the oxygen sensor heaters.

    Use cautionTool: digital multimeter, wiring diagram

    Warning:Let the exhaust cool before touching the sensor or its wiring. Back-probe connectors gently and never pierce insulation. If you are not comfortable reading a wiring diagram, a shop should do this step.

Symptoms

  • Check engine light, often with no change in how the car drives
  • Emissions test failure while the light is on
  • Reduced power or failsafe mode in some cases, which Kelley Blue Book lists Gets more serious: stop and have it checked.

How to fix

  1. With the exhaust fully cold, trace the downstream sensor's wiring to its connector and look for melted insulation, chafing on the exhaust or an A/C line, and a wet or corroded connector.

    Warning:Exhaust parts stay hot long after the engine stops. Wait at least an hour and never get under a car supported only by a jack.

  2. If your owner's manual lists a fuse for the oxygen sensor heaters, check that it is not blown, especially if more than one heater code is stored.

Parts and cost context

  • Oxygen (O2) sensor:Replace the downstream sensor only if its heater measures open or out of specification. Wiring, connector and supply faults set the same code and may need a connector or pigtail repair instead. 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

Ford

  • 2021–2022 · Bronco Sport

    Supported by vehicle data

    Ford's bulletin ties P0036 and P0138 on 2.0L engines to corrosion or water in two connectors. Check them before testing the sensor. Only the summary was read.

  • 2022 · Maverick

    Supported by vehicle data

    Ford ties P0036:00 and P0138:00, together with charging warnings, to water in connector C1050 on early-build 2.0L Maverick. Only the summary was read.

  • 2016–2018 · Edge

    Supported by vehicle data

    Ford has bulletins for P0036 on the 2.0L EcoBoost Edge; the summaries do not give the fix, so a dealer needs to say whether one applies.

  • 2015 · Mustang

    Supported by vehicle data

    Ford lists P0036 with other oxygen sensor codes on early-build 2.3L EcoBoost Mustang; the summary does not name the repair.

  • SSM 51048Status unverified

    2.0L Bronco Sport: MIL with P0036 and/or P0138

    2021–2022bronco-sport · NHTSA 10218901

    Inspect connectors C201 and C1570 for corrosion or water intrusion before workshop manual diagnosis, and replace a damaged connector with a pigtail kit and dielectric grease.

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

  • SSM 50973Status unverified

    2.0L Maverick: charging warning and MIL with P0036:00 and P0138:00

    2022maverick · NHTSA 10216960

    On 2022 Maverick built on or before 4-Apr-2022, inspect connector C1050 for water intrusion or corrosion; if found, replace it with a pigtail kit and apply dielectric grease. A twin bulletin, SSM 50993, carries the same text.

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

  • TSB18-2212Status unverified

    2.0L EcoBoost Edge: MIL with P0036 stored

    2016–2018edge · NHTSA 10144193

    For 2016-2018 Edge with the 2.0L EcoBoost built on or before 12-Mar-2018, follow the bulletin's service procedure for P0036 stored in the engine computer. The summary does not say what the procedure is. The 2016-2017 predecessor is TSB18-2097 (10137076).

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

  • 15-0078Status unverified

    2.3L EcoBoost Mustang: MIL with P0036, P0054, P0137 and/or P0141

    2015mustang · NHTSA 10058066

    Covers 2015 Mustang with the 2.3L EcoBoost built before 12/19/2014 that show the MIL with these codes. The summary does not say what the bulletin prescribes.

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

GMC

  • 2013–2015 · Acadia

    Supported by vehicle data

    GM's communication for 2013-2015 models lists P0036 among many O2 heater and sensor codes and points at harness wires chafed on the A/C hose coupling and an open Emission 1 fuse. Summary only.

  • PIT5336-acadiaStatus unverified

    MIL on with O2 sensor codes including P0036, possible open Emission 1 fuse

    2013–2015acadia · NHTSA 10135332

    Inspect and repair engine harness wires to the bank 1 O2 sensor that are chafed on the A/C hose coupling. The same communication covers the Buick Enclave and Chevrolet Traverse.

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

Buick

  • 2013–2015 · Enclave

    Supported by vehicle data

    GM's communication for 2013-2015 models lists P0036 among many O2 heater and sensor codes and points at harness wires chafed on the A/C hose coupling and an open Emission 1 fuse. Summary only.

  • PIT5336-enclaveStatus unverified

    MIL on with O2 sensor codes including P0036, possible open Emission 1 fuse

    2013–2015enclave · NHTSA 10135332

    Inspect and repair engine harness wires to the bank 1 O2 sensor that are chafed on the A/C hose coupling.

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

Chevrolet

  • 2013–2015 · Traverse

    Supported by vehicle data

    GM's communication for 2013-2015 models lists P0036 among many O2 heater and sensor codes and points at harness wires chafed on the A/C hose coupling and an open Emission 1 fuse. Summary only.

  • 2005 · Cobalt

    Possible — needs testing

    P0036 is one of several codes GM lists together on this bulletin; the summary gives no repair.

  • PIT5336-traverseStatus unverified

    MIL on with O2 sensor codes including P0036, possible open Emission 1 fuse

    2013–2015traverse · NHTSA 10135332

    Inspect and repair engine harness wires to the bank 1 O2 sensor that are chafed on the A/C hose coupling.

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

  • 3410Status unverified

    MIL on, possible no-crank, with P0443, P0102, P0036, P0030, P0135, P0101

    2005cobalt · NHTSA 10017236

    GM lists P0036 among several codes that may be set together. The summary does not state the repair.

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

Hummer

  • 2006 · H3

    Supported by vehicle data

    GM points to the powertrain relay when P0036 appears with other heater codes and a reduced engine power message.

  • 3508CStatus unverified

    SES light and reduced engine power with P0030, P0036, P0135, P0141, P1682, P2101

    2006h3 · NHTSA 10018910

    Inspect powertrain relay operation.

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

Cadillac

  • 01366Status unverified

    Service engine soon with O2 sensor DTCs P0138, P0151, adding P0030, P0036, P0050, P0056

    2004srx · NHTSA 10004150

    GM extended an O2 sensor code bulletin to include P0036. The summary gives no repair.

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

Ram

  • 2010–2012 · 2500

    Supported by vehicle data

    FCA's fix for oxygen sensor codes including P0036 is to replace the sensor connectors, not the sensors. Summary only.

  • 2010–2012 · 3500

    Supported by vehicle data

    FCA's fix for oxygen sensor codes including P0036 is to replace the sensor connectors, not the sensors. Summary only.

  • 25-004-12Status unverified

    MIL on due to oxygen sensor: replace O2 sensor connectors

    2010–20122500, 3500 · NHTSA 10128943

    P0036, P0037 and P0038 are among the oxygen sensor DTCs for which FCA replaces the O2 sensor connectors; the bulletin says not to replace parts first. Related bulletins 25-003-13 and 25-002-14 cover harness terminals and an overlay harness.

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

Nissan

  • 2016–2017 · Altima

    Supported by vehicle data

    Nissan says P0036 on 6-cylinder Altima should be diagnosed with the bank 2 A/F sensor heater procedure, so the sensor is not the bank 1 downstream sensor on that engine. Summary only.

  • 2016–2017 · Pathfinder

    Supported by vehicle data

    Nissan says P0036 on 6-cylinder Pathfinder should be diagnosed with the bank 2 A/F sensor heater procedure. Summary only.

  • NTB17-090Status unverified

    DTC P0036 diagnostic information

    2016–2017altima, pathfinder · NHTSA 10119252

    The service manual's P0036 information may be wrong for these 6-cylinder vehicles; follow the bank 2 A/F sensor heater open or shorted procedure.

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

Infiniti

  • 2016–2017 · Q70

    Supported by vehicle data

    Infiniti's twin of the Nissan bulletin says to diagnose P0036 as a bank 2 A/F sensor heater fault. Summary only.

  • 2016–2017 · QX50

    Supported by vehicle data

    Infiniti's twin of the Nissan bulletin says to diagnose P0036 as a bank 2 A/F sensor heater fault. Summary only.

  • 2016–2017 · QX60

    Supported by vehicle data

    Infiniti's twin of the Nissan bulletin says to diagnose P0036 as a bank 2 A/F sensor heater fault. Summary only.

  • 2016–2017 · QX70

    Supported by vehicle data

    Infiniti's twin of the Nissan bulletin says to diagnose P0036 as a bank 2 A/F sensor heater fault. Summary only.

  • ITB17-046Status unverified

    DTC P0036 diagnostic information

    2016–2017q70, qx50, qx60, qx70 · NHTSA 10117394

    The service manual's P0036 information may be inaccurate; follow the bank 2 A/F sensor heater open or shorted procedure.

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

  • P0037The heater control circuit for the downstream oxygen sensor on bank 1 is reading too low

    Same system Supported by vehicle data

    P0037 reports the downstream sensor's heater circuit as reading low, and P0038 as reading high. FCA's 2010-2012 Ram bulletin lists them together with P0036 as oxygen sensor heater faults. The same wiring and sensor checks apply.

  • P0030Oxygen sensor heater circuit fault on bank 1 sensor 1

    Same system Supported by vehicle data

    P0030 is the heater circuit fault on the upstream sensor. Stored together with P0036, it points to a shared feed such as a fuse or the powertrain relay, as GM's bulletins describe.

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

    Same system Possible — needs testing

    P0141 is a heater performance fault on the downstream sensor. GM's 2006 H3 bulletin lists it with P0036 and sends the technician to the powertrain relay.

  • P0138The downstream oxygen sensor on bank 1 is reporting a voltage that stays too high

    Shares causes Supported by vehicle data

    P0138 is the downstream sensor circuit reading high. Ford's Maverick and Bronco Sport bulletins list P0036 and P0138 together and trace both to water or corrosion in the same connectors, so check those first.

All Oxygen sensors codes

P0036 questions

Can I drive with P0036?

Usually yes for a short time, since the car normally drives as before. Kelley Blue Book advises against long periods with the code set, and the car will fail an emissions test while the light is on. If the check engine light flashes, stop driving.

Which sensor is bank 1 sensor 2?

Bank 1 is the side of the engine with cylinder 1, and an inline engine has only bank 1. Sensor 2 is the sensor after the catalytic converter. Check a diagram for your engine before ordering a part.

Do I have to replace the oxygen sensor?

Not always. Several carmakers' bulletins for this code point at corroded connectors or chafed wiring, and a lost fuse or relay feed sets it too. The sensor is replaced when its heater measures open or out of specification.

Sources and review

  1. P0036 trouble code: heated oxygen sensor 2, bank 1, heater control circuit — TroubleCodes.net
  2. P0036 code: HO2S heater control circuit, bank 1 sensor 2 — Kelley Blue Book
  3. Final Regulation Order: 13 CCR §1968.2, Malfunction and Diagnostic System Requirements (OBD II) for 2004 and later passenger cars, light-duty trucks and medium-duty vehicles — California Air Resources Board
  4. 2026 Honda Pilot Owner's Manual: Indicator Coming On/Blinking (Malfunction Indicator Lamp) — American Honda Motor Co.
  5. Ford TSB18-2212: 2.0L EcoBoost Edge, MIL with P0036 — Ford Motor Company (filed with NHTSA)
  6. GM PIT5336: MIL on with O2 sensor codes including P0036, wiring chafed on the A/C hose coupling — General Motors (filed with NHTSA)
  7. FCA 25-004-12: MIL on due to oxygen sensor, replace O2 sensor connectors — FCA US (filed with NHTSA)
  8. NHTSA complaint 11767161: 2017 Ford Edge, P0036 — NHTSA
  9. Nissan NTB17-090: DTC P0036 diagnostic information — Nissan North America (filed with NHTSA)
Last reviewed
Written by
Saurabh K.
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