OBD codes / P0064
P0064
ModerateO2 Sensor Heater Control Circuit High (Bank 2, Sensor 3)
You lose nothing by driving with P0064 while you arrange the fix — the affected sensor is a downstream monitor with no role in engine management. Repair it before your next emissions test, and enjoy having a trustworthy check-engine light again afterward.
What this code means
The final code in the heater-circuit family, P0064 belongs to the third oxygen sensor on Bank 2 — a position that exists only when the exhaust on the cylinder bank opposite cylinder 1 carries two catalytic converters in series, with this sensor mounted after the second one. Since Bank 2 itself requires a second cylinder bank, most inline-4 vehicles can never set this code. The sensor's electric heater is there to eliminate the slow natural warm-up so converter monitoring can start moments after a cold start; the computer sets P0064 when it detects excessive voltage in that heater's control circuit. 'High' faults trace to wiring shorted to battery voltage or to unwanted resistance — corroded terminals in a connector that has swallowed years of road spray, or a heater element drifting out of spec with age. The repair is most often a new sensor, but this rearmost harness run deserves a genuine inspection first. Whatever the cause, engine behavior is untouched: this sensor observes emissions hardware and never steers the fuel mixture.
Symptoms you might notice
- Check-engine light with the car driving exactly as before
- No measurable performance or economy effect
- Failed emissions inspection while the code is set
What it costs to fix
Typical range: $150–$425 · about ~0.5–1.5 hrs of labor
| If the cause is… | Part | Labor |
|---|---|---|
| Third (downstream) oxygen sensor | $30–$200 | ~0.5–1.5 hrs |
| Wiring / connector repair | $10–$120 | ~0.5–1.5 hrs |
| Heater-circuit fuse | $1–$10 | ~0.1–0.3 hrs |
Access to the rearmost Bank 2 sensor sets the labor; the sensor itself is generally an inexpensive downstream type. Where corrosion is the root cause, a connector repair pigtail plus an hour of labor is a common and much cheaper outcome than sensor replacement.
The price swings on which cause it turns out to be — so confirm the cause before paying. Diagnose P0064 for my exact vehicle →
Frequently asked
How does P0064 differ from P0062 and P0063?
All three concern the same Bank 2, Sensor 3 heater. P0062 is the generic 'something's wrong in the circuit' version, P0063 means the circuit voltage read low (short to ground or open element), and P0064 means it read high — a short to voltage or excess resistance. The letter of the fault steers the diagnosis.
Can I tackle P0064 in my driveway?
If you can get safely under the rear-center of the vehicle, yes — the job is an unplug-unscrew-replace with an O2 sensor socket. The honest obstacles are a sensor seized by years of heat and rust, and the discipline to inspect the fuse, wiring, and connector before spending money on the part.
Will this code cause me to fail smog or state inspection?
Under OBD-based emissions programs, yes — any active check-engine code fails, regardless of how cleanly the engine actually runs. After the repair, drive normally for several days so the heater and oxygen-sensor monitors complete before you retest.
Can P0064 damage other parts if I put it off?
No — the fault is self-contained in one sensor's heater circuit and doesn't stress the engine, converters, or electrical system. The only escalation risk is indirect: with the light already on, you won't notice if a new, more serious code joins it, so scan periodically if you delay the fix.
Seeing P0064 on your car? Get a diagnosis specific to your exact year, make and model.
Diagnose P0064 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.