P0050
HO2S Heater Control Circuit (Bank 2 Sensor 1)P0050 is a generic OBD-II powertrain diagnostic trouble code: HO2S Heater Control Circuit (Bank 2 Sensor 1). It is logged by the engine control unit when the powertrain monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.
What P0050 means
P0050 is a generic fault stored when the PCM detects a malfunction in the heater control circuit for Bank 2, Sensor 1 — the upstream (pre-catalyst) oxygen sensor on the opposite bank from cylinder 1. Bank 2 only exists on engines with two cylinder banks, such as V6, V8, and flat (boxer) engines. The Sensor 1 position means this is the primary fuel-control oxygen sensor for that bank, positioned before the catalytic converter in the Bank 2 exhaust stream.
The code is a general heater-circuit fault descriptor, meaning the PCM detected an abnormal condition but the fault has not been classified as specifically Low or High — or the manufacturer uses this code as an umbrella for any heater circuit fault on this sensor. The heater element is critical to bringing the sensor up to operating temperature quickly after a cold start; without it, Bank 2 fuel trim relies on open-loop maps for an extended warm-up period.
The underlying failure mechanism mirrors Bank 1 codes (P0031/P0032): failed heater element, open or shorted wiring, blown fuse, or PCM driver fault. On V-configuration engines the Bank 2 harness runs on the opposite side of the engine bay, making it important to confirm which bank cylinder 1 is on before starting diagnosis — this varies by manufacturer and model.
Common causes
Most-frequently reported root causes when P0050 is logged.
-
1
Failed internal heater element inside the Bank 2 Sensor 1 upstream oxygen sensor.
-
2
Open circuit or broken wire in the heater supply or control/ground leg of the Bank 2 sensor harness.
-
3
Short to chassis ground on the heater control wire, preventing the circuit from reaching operating current.
-
4
Short to battery voltage on the heater control wire, exceeding the maximum threshold.
-
5
Blown fuse or failed relay in the heater supply circuit for Bank 2.
-
6
Corroded, moisture-contaminated, or backed-out sensor connector on the Bank 2 side.
-
7
PCM heater output driver failure for the Bank 2 channel.
-
8
Physical damage to the harness from exhaust heat or road debris on the Bank 2 side of the engine.
Symptoms drivers notice
How to diagnose P0050
A typical diagnostic flow when this code is present.
-
1
Connect a scan tool and read all stored DTCs; use live heater current data if available — 0 A on the Bank 2 Sensor 1 heater channel confirms an open circuit.
-
2
Confirm which side of the engine is Bank 2 for the specific vehicle (Bank 2 is the side that does not contain cylinder 1; this varies by manufacturer — consult the service manual).
-
3
Inspect the Bank 2 Sensor 1 harness from the sensor in the exhaust manifold or downpipe back to the ECU connector for broken wires, melted insulation, and corrosion at connectors.
-
4
Check the heater circuit fuse for Bank 2 against the fuse diagram; replace any blown fuse and trace the cause before ordering a sensor.
-
5
With the sensor unplugged and ignition on / engine off, verify 12 V battery voltage is present on the heater supply pin at the harness connector on the Bank 2 side.
-
6
Measure continuity and resistance on the heater control/ground return wire from the connector back to the PCM pin; excessive resistance or an open indicates a harness fault.
-
7
Measure heater element resistance at the sensor's heater pins (typical: 2–30 Ω; infinite resistance confirms an open element); replace the sensor if the element has failed and no wiring faults were found.
Related powertrain codes
Frequently asked questions
Which side of the engine is Bank 2?
Bank 2 is the cylinder bank that does not contain cylinder number 1. For most GM and Chrysler V8s, Bank 1 is the driver's side and Bank 2 is the passenger side. For many Ford V8s it is reversed. Always verify bank orientation in the vehicle-specific service manual before diagnosing.
How does P0050 differ from P0031?
P0031 covers the heater circuit fault for Bank 1 Sensor 1 (upstream, cylinder-1 side). P0050 covers the same heater circuit fault for Bank 2 Sensor 1 (upstream, opposite bank). The diagnosis procedure is identical; only the physical location of the sensor and harness differs.
Does P0050 affect Bank 1 fuel control or catalytic converter monitoring?
No. P0050 only affects the Bank 2 upstream sensor. Bank 1 fuel trim and Bank 1 catalyst monitoring continue to function normally. Bank 2 will operate in open-loop during warm-up while the heater fault is present.
Can a single failed fuse cause both P0031 and P0050?
On some vehicles a single fuse supplies the heater circuit for multiple oxygen sensors. If both Bank 1 Sensor 1 and Bank 2 Sensor 1 heater codes appear together, check the shared fuse first before assuming both sensors have failed simultaneously.
Disabling P0050 in software
RaceTune can permanently disable P0050 — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.
Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.
Got P0050 in your scan?
Upload your ECU file — we'll identify the exact software version and confirm whether a disable is available for your car.
Upload your file