P0059
HO2S Heater Resistance (Bank 2, Sensor 1)P0059 is a generic OBD-II powertrain diagnostic trouble code: HO2S Heater Resistance (Bank 2, Sensor 1). 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 P0059 means
DTC P0059 indicates that the PCM has detected abnormal electrical resistance in the heater circuit of the Bank 2, Sensor 1 heated oxygen sensor. Bank 2 is the cylinder bank that does not contain cylinder number one; Sensor 1 is the upstream pre-catalyst sensor on that bank. This is the mirror equivalent of P0053 on the opposite engine bank, applicable to V-configuration and horizontally-opposed (boxer) engines. The heater element inside the sensor warms it to operating temperature — approximately 315–600 °C — within 20–30 seconds of cold start, enabling fast closed-loop fuel control on Bank 2. When the ECM measures heater circuit resistance outside the specified range (commonly 3–10 ohms) it logs P0059 and illuminates the MIL. Failure most often stems from a burnt-out heater element or wiring damage. Without a functioning heater, the Bank 2 sensor takes much longer to reach operating temperature, extending open-loop fuelling on that bank, increasing fuel consumption, and degrading catalyst efficiency. Ignoring P0059 long-term risks catalytic converter damage — replacement costs can exceed $1,000 — and will cause automatic failure at emissions inspections.
Common causes
Most-frequently reported root causes when P0059 is logged.
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1
Failed internal heater element in the Bank 2, Sensor 1 HO2S (burnt open, most common)
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2
Blown O2 HTR fuse (typically 15 A or 20 A in the underhood fuse box)
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3
Damaged, frayed, or heat-cracked wiring in the heater supply or return circuit on Bank 2
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4
Corroded connector pins or moisture ingress at the Bank 2 sensor harness plug
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5
Faulty heater relay or ECM heater-driver circuit for the Bank 2 sensor
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6
Exhaust manifold crack on Bank 2 allowing unintended oxygen infiltration
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7
Aftermarket oxygen sensor with incorrect heater element resistance installed
Symptoms drivers notice
How to diagnose P0059
A typical diagnostic flow when this code is present.
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1
Locate and inspect the O2 HTR fuse in the underhood fuse box — this is the quickest check and costs nothing
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2
Inspect the Bank 2 sensor wiring harness for heat damage, chafing against exhaust shields, or connector corrosion
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3
Unplug the sensor and measure heater pin resistance with a DVOM — outside 3–10 ohms (or OEM spec) confirms element failure; use OEM or OEM-equivalent replacement
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4
Back-probe the heater supply wire with ignition on to verify battery voltage is present when the heater circuit is commanded active
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5
Check the heater ground wire continuity from sensor plug to chassis ground (target < 0.5 ohm)
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6
After repair, clear codes, perform a cold-start drive cycle, and verify Bank 2 fuel trims return to ±5% in closed-loop
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7
If code resets with a new sensor, verify the replacement sensor's heater resistance matches OEM specification — generic aftermarket units are a common repeat-code cause
Related powertrain codes
Frequently asked questions
What is Bank 2 Sensor 1?
On engines with two cylinder banks (V6, V8, V10, boxer), Bank 2 is the bank that does not contain cylinder number one. Sensor 1 is the upstream oxygen sensor on that bank, located before the catalytic converter, responsible for closed-loop fuel control on the Bank 2 side.
How serious is P0059 if left unrepaired?
Bank 2 will run in open-loop fuelling for longer on cold starts, increasing fuel consumption by up to 5% and placing thermal stress on the Bank 2 catalytic converter. Long-term neglect can cause catalyst failure, leading to repair bills exceeding $1,000.
Why does the replacement sensor keep triggering P0059?
Aftermarket oxygen sensors frequently have heater element resistance outside the PCM's calibrated tolerance. Always verify that the replacement sensor's heater resistance matches the OEM specification, or use an OEM part (Motorcraft, ACDelco, Bosch OE, Denso OE, etc.).
Can P0059 appear on a 4-cylinder engine?
No. Four-cylinder engines are single-bank designs and only have Bank 1 circuits. P0059 is exclusive to multi-bank engines (V6, V8, flat-4 boxer, etc.) where a second exhaust bank is present.
Disabling P0059 in software
RaceTune can permanently disable P0059 — 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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