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P0037 — Ho2S Heater Control Circuit Low Bank 1 Sensor 2

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

Indicates the heater circuit for the downstream oxygen sensor on bank 1 is drawing less current than expected.

Symptoms

What causes it — most likely first

1. Faulty HO2S sensor

The heater element inside the sensor can fail, causing low current draw in the control circuit.

2. Wiring or connector damage

Corrosion, breaks, or loose pins in the heater circuit wiring or connector can restrict current flow.

3. Blown fuse or failed relay

A blown fuse or malfunctioning heater relay removes power to the sensor heater circuit.

4. PCM output circuit issue

A problem in the PCM's heater control output is possible but uncommon; it is typically considered only after other causes are ruled out.

How it's diagnosed

  1. Inspect wiring and connectors for damage or corrosion
  2. Check the heater circuit fuse and relay for continuity
  3. Measure resistance of the sensor heater circuit
  4. Test heater voltage at the sensor while the engine is running
  5. Replace the sensor or repair wiring as needed
  6. If all else fails, evaluate the PCM output circuit

Code facts & related codes

SystemPowertrain (engine & transmission)
StandardizationSAE generic — identical on every make
Related codesP0030 — Ho2S Heater Control Circuit Bank 1 SenP0031 — Ho2S Heater Control Circuit Low Bank 1P0032 — Ho2S Heater Control Circuit High Bank P0033 — Turbochargersupercharger Bypass Valve P0034 — Turbochargersupercharger Bypass Valve P0035 — Turbochargersupercharger Bypass Valve

Frequently asked

Do I need to replace the PCM to fix P0037?

Usually not; PCM failure is rare and is only considered after the sensor, wiring, fuse, and relay have been inspected and tested.

Can a blown fuse cause this code?

Yes; a blown fuse in the heater circuit will cut power to the sensor heater and trigger P0037.

Is it safe to drive with this code?

The vehicle may still run, but it can experience reduced fuel efficiency and may fail an emissions inspection; it should be addressed promptly.

How can I test the heater circuit?

Use a multimeter to measure resistance across the heater leads and check for proper voltage when the engine is on.