HO2S Heater Control Circuit High (Bank 2, Sensor 3)
The oxygen sensor heater on Bank 2, Sensor 3 (post-catalyst) isn't working properly—it's getting too much voltage instead of the right amount. Think of it like a heating element stuck in the 'on' position when it should be modulating.
The ECU monitors the heater control circuit voltage for the post-catalyst oxygen sensor. It expects the heater to cycle on and off or modulate to maintain a target resistance. A fault occurs when the measured voltage remains continuously high, indicating the heater is stuck on or the circuit is shorted to power.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Heater Control Voltage | 0–12V modulated/cycled | >12V continuous or stuck high |
| Heater Resistance | 2–14 ohms (varies by design) | Out of range or shorted |
Code P0064 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.
Once the fault is repaired, P0064 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.
The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.