P0037 — HO2S Heater Control Circuit Low (Bank 1 Sensor 2)
Low severityWhat it means
P0037 is stored when the engine control unit sees a fault involving the oxygen sensor heater circuit (bank 1 sensor 2). The heater brings the oxygen sensor up to operating temperature quickly so the control unit can use it for fuel control soon after a cold start. A “low” reading means the signal is stuck near the bottom of its range, which usually points to a short to ground or an internally failed sensor.
Common symptoms
- The live reading sits abnormally low or at zero
- Usually only a check engine light
- Slightly worse fuel economy until the sensor warms up
- A possible failed emissions test
Likely causes
- Signal wire shorted to ground
- Internally failed sensor pulling the signal low
- Open or burned-out sensor heater element
- Blown fuse or wiring/connector fault to the heater
What to check first
- Compare the live signal against a known-good range and check for a short to ground
- Check the heater fuse and the sensor's power and ground
- Measure the heater element resistance against specification
Can you keep driving?
Safe to drive short-term; it mainly affects cold-start fuelling and emissions, so repair to pass inspection.
Frequently asked questions
What is the most common cause of P0037?
The most likely cause is: Signal wire shorted to ground. Several other faults can set P0037 as well, so confirm the real cause with live data and the checks above before replacing any parts.
Can I just clear P0037 and keep driving?
Clearing P0037 with an OBD2 scanner turns the warning light off, but if the underlying fault has not been repaired the code will usually come back within a few drive cycles. Fix the cause first, then clear the code to confirm the repair worked.
How serious is P0037?
P0037 is a low-severity code. It rarely affects how the car drives, but it is still worth fixing so the engine runs efficiently and passes an emissions test.
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