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P0059 — Ho2S Heater Resistance Bank 2 Sensor 1

Generic OBD-II · all makesPowertrain (engine & transmission)

P0059 indicates that the Powertrain Control Module (PCM) has detected a heater resistance circuit fault in the oxygen sensor (Bank 2, Sensor 1). The heater circuit is not within the expected resistance range, which can prevent the sensor from reaching its operating temperature.

Symptoms

What causes it — most likely first

1. Heated O2 sensor (Bank 2, Sensor 1) failure

The sensor's internal heater element may be open, shorted, or have degraded resistance beyond specification.

2. Corroded or broken heater circuit wiring

Damage to the wiring harness or connector pins can cause high resistance or an open circuit.

3. Loose, damaged, or contaminated sensor connector

Poor electrical contact due to corrosion, bent pins, or a loose plug can produce erratic resistance readings.

4. Faulty PCM heater‑circuit driver

A rare internal failure in the PCM’s driver circuit could misread a good sensor as faulty.

How it's diagnosed

  1. Scan for additional OBD‑II codes and verify that P0059 is the only active sensor‑related code.
  2. Perform a visual inspection of the Bank 2, Sensor 1 heater wiring and connector for damage, corrosion, or looseness.
  3. Measure the heater resistance of the sensor with a multimeter and compare it to the manufacturer’s specification (typically 3–5 Ω).
  4. If the sensor resistance is out of range, replace the sensor; if it is within spec, test continuity of the heater circuit wiring back to the PCM.
  5. If wiring and sensor are good, perform a PCM heater‑circuit output test (voltage on the heater circuit when the engine is on) to confirm driver operation.

Code facts & related codes

SystemPowertrain (engine & transmission)
StandardizationSAE generic — identical on every make
Related codesP0050 — Ho2S Heater Control Circuit Bank 2 SenP0051 — Ho2S Heater Control Circuit Low Bank 2P0052 — Ho2S Heater Control Circuit High Bank P0053 — Ho2S Heater Resistance Bank 1 Sensor 1P0054 — Ho2S Heater Resistance Bank 1 Sensor 2P0055 — Ho2S Heater Resistance Bank 1 Sensor 3

Frequently asked

Can the PCM be the cause of a P0059 code?

It is possible but uncommon. Most P0059 cases are due to a faulty sensor, wiring, or connector. Replacing the PCM should be a last resort after confirming the sensor and wiring are good.

Do I need to replace the oxygen sensor immediately?

If the heater resistance is out of specification, the sensor should be replaced. Driving with a non‑functional heater can lead to prolonged warm‑up times, higher emissions, and possible damage to the sensor.

Will a bad O2 sensor heater cause poor fuel economy?

Yes. The sensor may remain in open‑loop operation longer, causing the engine to run richer and reducing fuel efficiency.

Is it safe to clear the code without fixing the problem?

Clearing the code will turn off the Check Engine Light temporarily, but the PCM will set the code again if the fault persists, and the vehicle may fail emissions testing.