OBD codes / P0050
P0050
ModerateO2 Sensor Heater Control Circuit (Bank 2, Sensor 1)
P0050 won't stop you from driving — the sensor still functions once exhaust heat warms it; the heater fault just delays accurate fuel control after cold starts. Address it reasonably soon for the sake of fuel economy and emissions testing, and rule out the cheap fuse before paying for a sensor.
What this code means
P0050 is the Bank 2 twin of P0030: a fault in the heater control circuit of an upstream oxygen sensor, but on the opposite side of the engine from cylinder 1. Bank 2 only exists on engines with two separate cylinder banks — V6s, V8s, and flat/boxer engines — so this code shouldn't appear on most inline-4s, which have just one bank. The sensor in question sits before the catalytic converter on that second bank, and its built-in heater is what lets it start reporting the air-fuel mixture within seconds of a cold start, enabling early closed-loop fuel control. A generic circuit fault here usually means the heater circuit is open or not responding when commanded — most often a burned-out heater element inside the sensor, with a blown fuse or wiring/connector damage as the other realistic causes. Until repaired, that bank's fuel trim runs on estimates for a few extra minutes after cold starts, costing a little fuel and adding a little emissions output but nothing dramatic.
Symptoms you might notice
- Check-engine light with normal driving behavior
- Slightly increased fuel consumption on cold starts and short trips
- Possible emissions-test failure while the code is set
What it costs to fix
Typical range: $150–$475 · about ~0.3–1.2 hrs of labor
| If the cause is… | Part | Labor |
|---|---|---|
| Upstream oxygen (O2) sensor | $40–$250 | ~0.3–1.2 hrs |
| Wiring / connector repair | $10–$120 | ~0.5–1.5 hrs |
| Heater-circuit fuse | $1–$10 | ~0.1–0.3 hrs |
On V-type engines the Bank 2 sensor often sits on the firewall side or under intake plumbing, so it can take more labor than its Bank 1 counterpart on the same vehicle. Wideband upstream sensors and OEM parts push toward the high end of the part range.
The price swings on which cause it turns out to be — so confirm the cause before paying. Diagnose P0050 for my exact vehicle →
Frequently asked
Which side of my engine is Bank 2?
Bank 2 is the cylinder bank that does not contain cylinder 1. Which physical side that is varies by manufacturer and engine orientation, so check a diagram for your specific engine before buying or replacing a sensor — Bank 1/Bank 2 mix-ups are one of the most common wasted-money mistakes with these codes.
Why doesn't P0050 apply to most 4-cylinder cars?
An inline-4 has all cylinders in a single bank, so it only has Bank 1 sensors and Bank 1 codes. Bank 2 codes like P0050 belong to V6, V8, V10, and flat/boxer engines, which split their cylinders across two banks with separate exhaust paths.
Can I drive with P0050 for now?
Yes — it's a warm-up-speed problem, not a running problem. You'll burn slightly more fuel right after cold starts and the check-engine light will stay on, but the engine is in no danger. Fix it before an emissions inspection.
What's the likely fix for P0050?
Nine times out of ten in this code family it ends with a new Bank 2, Sensor 1 oxygen sensor, because the heater element that failed lives inside it. The exceptions worth checking first: a blown heater fuse and a damaged or corroded connector.
Seeing P0050 on your car? Get a diagnosis specific to your exact year, make and model.
Diagnose P0050 for my vehicleRelated trouble codes
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Generic OBD-II reference. Manufacturer-specific behavior varies — confirm with a scan tool and, for safety-related codes, a professional inspection.