P0061
HO2S Heater Resistance (Bank 2, Sensor 3)P0061 is a generic OBD-II powertrain diagnostic trouble code: HO2S Heater Resistance (Bank 2, Sensor 3). It is logged by the engine control unit when the powertrain monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.
What P0061 means
Diagnostic trouble code P0061 is set when the Powertrain Control Module measures the heater element resistance of the third heated oxygen sensor on Bank 2 (the cylinder bank not containing cylinder 1) outside the programmed acceptable range. On vehicles equipped with a third oxygen sensor — commonly found in systems with dual catalytic converters or secondary air injection monitoring — Sensor 3 sits furthest downstream and serves as an additional check on downstream catalyst and exhaust aftertreatment efficiency. The internal heater element brings the sensor to its minimum operating temperature of roughly 300–350 °C far more quickly than exhaust heat alone, enabling accurate voltage output from startup. The PCM monitors heater circuit resistance by applying a voltage and measuring current; typical specification is approximately 8 Ohms at room temperature, with deviations of ±10% or greater triggering this fault. Common failure modes include an open heater element (infinitely high resistance), wiring damage from road debris or exhaust heat, connector corrosion, or a failed upstream fuse. Because this is a downstream monitoring sensor rather than a primary fuel control sensor, drivability effects are typically mild but fuel economy and cold-start emissions can worsen noticeably.
Common causes
Most-frequently reported root causes when P0061 is logged.
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1
Failed or open heater element inside the Bank 2 Sensor 3 oxygen sensor
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2
Heat-damaged wiring harness or connector due to proximity to exhaust components
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3
Corroded or broken connector pins at the sensor plug
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4
Blown heater-circuit fuse or failed fusible link upstream of the sensor
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5
Road debris impact damage to the sensor body or wiring
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6
Faulty engine control relay interrupting heater circuit power supply
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7
Rare PCM failure causing incorrect heater circuit resistance monitoring
Symptoms drivers notice
How to diagnose P0061
A typical diagnostic flow when this code is present.
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1
Scan for all active and pending DTCs; record freeze frame data and prioritise any codes that may affect sensor accuracy (misfires, rich/lean faults) and resolve them first
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2
Check for manufacturer Technical Service Bulletins specific to the vehicle, as some models have known wiring routing issues near the exhaust that cause premature heater failures
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3
Visually inspect the wiring harness from the PCM to the Bank 2 Sensor 3 connector; look for heat blistering, chafed insulation, and corrosion at connector pins
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4
Locate and test the heater-circuit fuse and fusible link; measure fuse voltage drop under load and replace any blown component
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5
Disconnect the sensor and measure resistance across the two heater terminals with a digital multimeter at room temperature; a reading well above 10 Ohms or an open circuit confirms heater element failure requiring sensor replacement
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6
Verify reference voltage at the sensor connector power wire (key on, engine off) should match battery voltage; absence of voltage indicates a wiring or relay fault upstream
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7
Use OEM-specification replacement sensors; aftermarket sensors frequently exhibit resistance drift that causes the code to recur
Related powertrain codes
Frequently asked questions
What is the difference between P0061 and P0060?
Both codes indicate abnormal heater element resistance on Bank 2, but P0060 refers to Sensor 2 (the first downstream sensor after the main catalytic converter) while P0061 refers to Sensor 3 (a further-downstream sensor used in vehicles with dual converters or secondary aftertreatment). P0061 is therefore less common as it only appears on vehicles equipped with a third sensor in the exhaust.
Does P0061 put the vehicle into limp mode?
Typically not. Because Sensor 3 is a downstream monitoring sensor rather than a primary fuel control input, the PCM generally continues normal operation and only illuminates the MIL. However, sustained cold-start enrichment from a slow-warming sensor can occasionally cause rough running.
Can I drive indefinitely with P0061?
Short-term driving is unlikely to cause immediate damage, but the MIL will cause an emissions test failure, and prolonged incorrect cold-start fuelling increases fuel dilution of engine oil and accelerates spark plug wear.
How do I know which sensor is Sensor 3 on my vehicle?
Sensor 3 on Bank 2 is the third oxygen sensor counting from the engine on the bank that does not contain cylinder 1. On most V6/V8 applications this is located at the outlet of the second or underbody catalytic converter on the Bank 2 side. Always consult a vehicle-specific exhaust diagram or factory wiring schematic to confirm the physical location.
Disabling P0061 in software
RaceTune can permanently disable P0061 — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.
Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.
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