Code
P0064
Generic
P — Powertrain
HO2S Heater Control Circuit High Bank 2 Sensor 3
Views:
UK: 19
EN: 59
RU: 37
AI status
Completed
Completed
100%
Causes
- Open or damaged heater element inside the oxygen sensor
- Broken, corroded or disconnected wiring or connector for the heater circuit
- Short to battery voltage (power feed) in the heater control wiring
- Blown fuse or failed relay supplying the sensor heater
- Poor engine/chassis ground affecting heater circuit
- Faulty PCM or driver output (less common)
Symptoms
- Check Engine Light (MIL) illuminated
- Stored P0064 (may be accompanied by other O2 heater codes)
- Failed emissions readiness for oxygen sensor heater
- Reduced fuel trim accuracy and possible drivability complaints (in some cases)
- Possible poorer fuel economy
What to check
- Read and record freeze frame and related DTCs with a scan tool
- Visual inspection of the Bank 2 Sensor 3 harness and connector for damage, corrosion, heat damage, or contamination
- Verify fuses and relays for the oxygen sensor heater circuit
- Backprobe the sensor connector to check for heater supply voltage (battery) and control signal
- Measure heater element resistance at the sensor (compare to spec)
- Check for continuity to battery positive (short to power) and continuity to ground (short to ground or open)
Signal parameters
- Heater supply voltage: ~11–14 V (battery voltage) at the heater power feed with ignition ON
- Heater element resistance (typical): low single-digit to tens of ohms (commonly in the 2–20 Ω range; vehicle-specific)
- When PCM commands heater ON: control path should complete and allow current flow (measurable current draw; exact current depends on sensor design)
- Open/high resistance or high voltage on the control line indicates a fault in the heater circuit
Diagnostic algorithm
- Verify the code: retrieve freeze-frame data and any related O2 heater or oxygen sensor codes.
- Visual inspection: examine the Bank 2 Sensor 3 connector and wiring for corrosion, loose terminals, heat damage, cuts, or rodent chew. Repair any obvious damage.
- Check fuses/relays: locate and test the fuse(s) and relay(s) that feed the O2 heater circuits; replace if blown/faulty.
- Backprobe connector: with ignition ON (engine off), backprobe the sensor connector to identify the heater power feed and the PCM control/monitor circuit. Confirm battery voltage on the supply feed.
- Measure heater resistance: disconnect sensor and measure resistance across the heater pins at the sensor. If open or well above spec, replace the sensor.
- Check for shorts/opens: with harness disconnected, check continuity from the sensor connector to the fuse/relay and to the PCM. Check for short to battery (unexpected continuity to B+) or short to ground where not expected.
- Command heater on: using a capable scan tool, command the heater ON and observe voltage/current behavior; verify the PCM driver is switching as expected.
- Repair wiring or replace sensor: repair damaged wiring, clean/replace connector, or replace the oxygen sensor heater if out of spec. Use OEM or equivalent replacement sensor.
- Clear codes and verify: clear DTCs, perform drive cycle / road test and recheck for code reappearance and readiness status. If code returns and wiring and sensor test good, consider PCM diagnosis.
Likely causes
- Sensor heater element failed (open or high resistance)
- Connector pins corroded or pushed out
- Wiring harness damaged by heat, chafing, or rodent damage
- Fuse for heater circuit blown or relay stuck
- Short to Vb (battery) on the control/feedback circuit
Fault status
Status
Heated oxygen sensor (HO2S) heater control circuit voltage high for Bank 2 Sensor 3 — indicates open/high-resistance heater circuit, short to voltage, bad connector/fuse, or control module issue.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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