Fuel & air metering · Powertrain · generic (SAE-defined)
P0050: HO2S Heater Control Circuit (Bank 2 Sensor 1)
P0050 means the engine computer detected a fault in the heater circuit of the upstream oxygen sensor on Bank 2, the side of the engine without cylinder 1.
Standard title per SAE J2012 / ISO 15031-6 · Updated 2026-11-07 · By CarWhere Research
How P0050 sets
The upstream heated oxygen sensor (HO2S) on Bank 2 uses an internal heater to reach operating temperature quickly. The powertrain control module (PCM) controls this heater and monitors the circuit. An open, short or out-of-range reading in the Bank 2 Sensor 1 heater circuit sets P0050. It applies only to engines with two banks or dual exhaust sensor layouts.
Common causes of P0050
Roughly most likely first; the actual cause depends on the vehicle and needs testing to confirm.
- Failed heater in the Bank 2 Sensor 1 oxygen sensor
- Heat-damaged or chafed sensor wiring
- Corroded or loose connector
- Blown heater fuse
- Faulty heater relay where fitted
- PCM driver fault (uncommon)
P0050 symptoms
- Check engine light on
- Often no drivability symptoms
- Slightly reduced fuel economy
- Delayed closed-loop operation after cold start
How P0050 is diagnosed
- Scan for codes; check for P0030 or other heater codes that could share a fuse
- Inspect the Bank 2 upstream sensor wiring and connector
- Check fuse and supply voltage
- Measure heater resistance and compare to specification
- Test the PCM control circuit for opens or shorts
- Repair, clear codes and confirm
Typical fixes for P0050
- Replace the Bank 2 Sensor 1 oxygen sensor
- Repair wiring or connector damage
- Replace the fuse and fix the short
- Replace a failed heater relay
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
P0050 FAQ
What does code P0050 mean?
P0050 means the engine computer detected a fault in the heater circuit of the upstream oxygen sensor on Bank 2, the side of the engine without cylinder 1. The standard definition is "HO2S Heater Control Circuit (Bank 2 Sensor 1)."
Can I drive with a P0050 code?
Yes, the vehicle can usually be driven normally. Expect possible slight fuel economy loss after cold starts and an emissions test failure until it is repaired.
Which side of the engine is Bank 2?
Bank 2 is the side opposite cylinder 1. The service manual or engine diagram shows which cylinder is number 1.
If P0030 and P0050 set together, what is likely?
Both upstream heaters failing at once is less likely than a shared fuse, relay or power feed problem, so check those first.
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.