P0064 code: O2 Sensor Heater Control Circuit High (Bank 2, Sensor 3)
P0064 means o2 Sensor Heater Control Circuit High (Bank 2, Sensor 3). The code says where to look, not what failed — the fix depends on which cause your car actually has.
What P0064 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.
P0064 symptoms
- 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 P0064
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 →
How to fix P0064
Moderate — doable at home with common tools and patience
- Clean and inspect the rearmost connector
Sensor 3 on Bank 2 hangs at the far end of the exhaust, and its plug has seen years of road spray. Open it and look for pitted or green heater terminals and a perished seal; that corrosion adds resistance, one of the textbook causes of a high reading. Clean the terminals properly or fit a repair connector.
- Measure the heater cold and compare with spec
With the exhaust cold, read across the heater pins and compare with the service-manual value for this sensor. A heater well above spec, even with continuity, is aging out and can set P0064 on its own.
- Plug in a known-good sensor without installing it
To separate sensor from circuit, connect a new sensor to the harness and secure it clear of fuel lines, wiring and moving parts — its tip gets very hot in open air. Clear codes and run the engine for a few minutes. If P0064 stays away, the old sensor is confirmed; if it returns, the fault is in the wiring or the engine computer.
- Voltage-drop the control path to the engine computer
With the heater commanded on, measure the drop between the sensor's control terminal and the matching pin at the computer connector. More than a few tenths of a volt along that long run means resistance in a splice or connector. Also check that wire for battery voltage with the sensor unplugged, which would mean a short to a live circuit.
- Escalate if a good sensor still sets it
With a known-good sensor and a clean, low-resistance circuit, the remaining suspect is the heater driver inside the engine computer. That needs proper confirmation, and a replacement computer typically needs programming, so this is the point to hand it to a shop.
DIY or shop? The connector cleaning, resistance check and substitution test are all realistic home jobs with a multimeter and a safe way under the car. Voltage-drop testing along a long rear harness is slower but doable with long test leads. It becomes shop work at the engine computer: confirming a failed heater driver and programming a replacement take dealer-level tools, and a short to voltage inside the body loom is faster to find with a wiring diagram and a lift.
Tools for the DIY steps: Multimeter with long test leads · Terminal cleaning brush · Zip ties (for the substitution test) · Jack stands or ramps · O2 sensor socket
Not sure which step applies to your car? Get the likely cause for your exact vehicle before buying anything for P0064.
Start a case with P0064 and your car. Redline weighs these causes against what your car shows, and names the check that would settle it before you buy parts.
Can I drive with P0064?
Redline can’t determine from a symptom or code alone whether your car is safe to drive.
P0064: common questions
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, it will — any active check-engine code fails, regardless of how cleanly the engine actually runs. After the repair, allow several days of ordinary driving 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.
Related trouble codes
Don’t have a scanner yet? A ~$25 Bluetooth adapter reads codes like P0064 from your phone. See our guide to the best OBD2 Bluetooth adapters. Run a repair shop? See Redline for shops.
Generic OBD-II reference. Manufacturer-specific behavior varies. Confirm with a scan tool and, for safety-related codes, a professional inspection. Cost ranges are reference ranges, not quotes.
Seeing P0064 on your car?
Every problem becomes a Case. Tell Redline what the car is doing: it shows what the evidence supports, what’s still missing, and what to check next, before you approve a repair.
“Inner pad ~1 mm. Outer pad 3 mm.”
Next: check the slide pins move freely before buying parts.