P0037
HO2S Heater Control Circuit Low (Bank 1 Sensor 2)
The engine computer is not seeing the correct electrical signal for the heater in the rear oxygen sensor on bank 1. This usually means the heater circuit is open, shorted, or the sensor heater has failed. It can cause poor emissions control and a check engine light.
- SEV
- 2/5
- DRIVE
- CAUTION
- DIY
- $20–$120
- SHOP
- $120–$350
Quick answer
AI-CITATION READYWhat it means
Can you drive with it?
Most common causes
- Failed bank 1 sensor 2 oxygen sensor heater element
- Damaged, corroded, or loose wiring or connector at the rear O2 sensor
- Blown heater circuit fuse or power supply issue
Typical repair cost
DIY usually runs $20–$120. Typical shop repair lands around $120–$350, depending on the root cause.
01 / Definition
P0037 sets when the PCM detects a low voltage or low current condition in the heater control circuit for the downstream heated oxygen sensor on bank 1, sensor 2. The heater is used to bring the sensor up to operating temperature quickly so the PCM can monitor catalyst efficiency and control emissions properly. A failure in the sensor heater, wiring, fuse, relay, or PCM driver can trigger this code.
02 / Drive status
With caution. The vehicle is usually still drivable, but fuel control and emissions monitoring may be affected. Have it repaired soon, especially if the check engine light is flashing or other codes are present.
03 / Symptoms
- Check engine light
- Stored P0037 code
- Possible increased fuel consumption
- Failed emissions test
- Delayed oxygen sensor warm-up
- Other O2 sensor or catalyst-related codes
04 / Causes
| 1 | Failed bank 1 sensor 2 oxygen sensor heater element | high |
|---|---|---|
| 2 | Damaged, corroded, or loose wiring or connector at the rear O2 sensor | high |
| 3 | Blown heater circuit fuse or power supply issue | medium |
| 4 | Short to ground or short to power in the heater circuit | medium |
| 5 | Failed PCM driver circuit | low |
| 6 | Exhaust damage or contamination affecting the sensor harness | low |
05 / Diagnostic sequence
- 01Confirm the code and check for related O2 sensor, heater, or power supply codes.
- 02Inspect the bank 1 sensor 2 connector and wiring for heat damage, corrosion, melted insulation, or loose pins.
- 03Check the fuse and power feed for the oxygen sensor heater circuit.
- 04Measure heater circuit resistance at the sensor and compare it to specifications.
- 05Verify battery voltage and ground control at the heater connector with the key on or engine running as required by the vehicle.
- 06Wiggle-test the harness while monitoring voltage or resistance for intermittent faults.
- 07If wiring and power are good, test or replace the sensor; if the problem remains, check the PCM driver circuit.
06 / Repairs
| 1 | Repair damaged wiring, terminals, or connector at bank 1 sensor 2 | $20–$150 |
|---|---|---|
| 2 | Replace blown fuse or correct the underlying short or power supply fault | $10–$80 |
| 3 | Replace the bank 1 sensor 2 oxygen sensor | $50–$250 |
| 4 | Diagnose and repair PCM control circuit issues if all other checks pass | $150–$600 |
07 / Related codes
08 / FAQ
What does bank 1 sensor 2 mean?
Bank 1 is the side of the engine with cylinder 1. Sensor 2 is the downstream oxygen sensor, located after the catalytic converter.
Can a bad oxygen sensor heater cause drivability problems?
Usually it causes an emissions problem more than a drivability problem, but fuel economy and emissions can suffer.
Will clearing the code fix P0037?
No. The code will return if the heater circuit fault is still present.
Is the upstream or downstream sensor involved?
P0037 refers to the downstream sensor on bank 1, not the upstream sensor.
09 / Source and method
- DATA BASIS
- OBD-II REFERENCE + OBD2.HELP
- METHOD
- STATIC VALIDATION
- SAFETY
- INFORMATIONAL
This page combines OBD-II diagnostic reference data with OBD2.help generated diagnostic guidance for code meaning, likely causes, and repair direction.
Publishing uses deterministic schema and build validation, plus manual spot checks on representative pages before release.
Safety-critical diagnosis and repairs should be confirmed with a qualified mechanic, especially when the vehicle is misfiring, overheating, or losing power.