P0063: HO2S Heater Control Circuit Low (Bank 2, Sensor 3)

What does P0063 mean?

P0063 is a diagnostic trouble code indicating "HO2S Heater Control Circuit Low (Bank 2, Sensor 3)". The ECU is detecting a voltage reading that is below the expected range in the o2 sensors circuit. This typically points to a wiring short, a faulty sensor, or a grounding issue.

Symptoms you may notice

• Check engine light (MIL) illuminated on dashboard
• Intermittent warning lights
• Erratic gauge readings

Common causes

• Damaged or corroded wiring harness
• Loose or disconnected electrical connector
• Failed o2 sensors sensor or actuator
• Blown fuse in the related circuit
• Poor ground connection

What should you do?

This code sits in an engine peripheral, typically emissions or forced induction. It will not take braking or steering away, but it can put the car into limp mode, cost you fuel and fail a roadworthy. Book it in rather than clearing it and hoping.