Fuel & air metering · Powertrain · generic (SAE-defined)
P0036: HO2S Heater Control Circuit (Bank 1 Sensor 2)
P0036 means there is a fault in the heater circuit of the downstream oxygen sensor on Bank 1, the sensor located after the catalytic converter.
Standard title per SAE J2012 / ISO 15031-6 · Updated 2026-11-07 · By CarWhere Research
How P0036 sets
The downstream heated oxygen sensor (HO2S) has an internal heater so it can give accurate readings quickly. The powertrain control module (PCM) switches that heater and checks the circuit for the expected electrical behavior. An open, short or abnormal current in the Bank 1 Sensor 2 heater circuit sets P0036.
Common causes of P0036
Roughly most likely first; the actual cause depends on the vehicle and needs testing to confirm.
- Burned-out heater in the Bank 1 Sensor 2 oxygen sensor
- Damaged wiring under the vehicle from road debris or heat
- Corroded connector
- Blown heater fuse
- Faulty PCM heater driver (uncommon)
P0036 symptoms
- Check engine light on
- Usually no change in drivability
- Catalyst monitor may show not ready
- Possible emissions test failure
How P0036 is diagnosed
- Scan for codes and check readiness monitors
- Inspect the downstream sensor wiring and connector under the vehicle
- Check the heater fuse and supply voltage
- Measure heater resistance at the sensor
- Check the PCM control circuit for continuity and shorts
- Repair and verify with a drive cycle
Typical fixes for P0036
- Replace the Bank 1 Sensor 2 oxygen sensor
- Repair the wiring or connector
- Replace the fuse and fix the underlying short
Replace parts only after testing confirms the cause — a code names the circuit or condition that failed a check, not necessarily the faulty part. We don’t publish per-repair prices; for what households actually spend on upkeep, see car repair costs.
Related codes & warning lights
P0036 FAQ
What does code P0036 mean?
P0036 means there is a fault in the heater circuit of the downstream oxygen sensor on Bank 1, the sensor located after the catalytic converter. The standard definition is "HO2S Heater Control Circuit (Bank 1 Sensor 2)."
Can I drive with a P0036 code?
Yes, this code rarely affects how the vehicle runs. It should still be fixed soon because catalytic converter monitoring cannot run properly and the vehicle may fail an emissions test.
Will P0036 hurt fuel economy?
Usually not noticeably, because the downstream sensor mainly checks catalytic converter performance rather than setting the fuel mixture.
Is P0036 related to a bad catalytic converter?
Not directly. It is an electrical heater fault, though it can prevent the PCM from completing its catalyst check.
Keep researching
Engine guides by brand (known issues, specs)
More fuel & air metering codes
Sources
- SAE J2012 — Diagnostic Trouble Code Definitions (standard code titles)
- ISO 15031-6 — Road vehicles: communication between vehicle and external equipment for emissions-related diagnostics, Part 6: Diagnostic trouble code definitions
- U.S. EPA — Vehicle Emissions Inspection and Maintenance (I/M) programs
- U.S. EPA, 40 CFR 86.1806-17 — Federal onboard diagnostics requirements for light-duty vehicles
- California Air Resources Board — On-Board Diagnostic (OBD) Program
General information written by CarWhere Research, not a diagnosis of your vehicle. Manufacturers can add their own sub-definitions and test conditions; confirm with the factory service information for your year, make and model. Before paying for a repair, check NHTSA for open recalls and your warranty booklet: federal law requires an emissions warranty on major emission-control parts such as the catalytic converter and engine computer.