P0037 Oxygen sensor heater control circuit low (bank 1, sensor 2)
What P0037 means
The engine computer sees a voltage or current that is too low in the heater circuit of the downstream oxygen sensor on bank 1. This usually means the heater is not getting power or the heater element has failed, so the sensor stays cold and the catalyst check cannot run.
P0037 is a generic SAE J2012 code: it means the same on every make. The exact cause still depends on the car, so read the freeze-frame data before replacing parts.
At a glance
- Severity
- Medium
- Typical repair cost
- 80–350 €
- Workshop time
- 0.5–1.5 h
- Repair difficulty
- Easy
- DIY possible
- Yes
- Check engine light
- Yes
- Affects emissions test
- Yes
Parts and labour at an independent workshop in Europe. Main dealers charge more; the cause decides the bill, not the code.
Symptoms
- Check engine light on
- Car usually drives normally
- Catalyst readiness monitor not completing
- Possible failed emissions test
Common causes
- Burnt-out heater element in the downstream oxygen sensor
- Blown fuse in the oxygen sensor heater supply
- Broken or chafed wire, or a loose or corroded connector
- Heater control wire shorted to ground
Can I keep driving with P0037?
You can keep driving, but book a repair within a week or two. Engine running is rarely affected, but the car will not pass an emissions test with this fault.
What to check first
- Check the oxygen sensor heater fuse first; a blown fuse points to a short in the heater or its wiring.
- Inspect the connector and harness to the downstream sensor for broken, chafed or corroded wires.
- Measure the heater resistance at the sensor; an open or very high reading means the sensor needs replacing.
- Check supply voltage and continuity of the control wire back to the engine control unit before fitting a new sensor.
Related codes
- P0036 Oxygen sensor heater control circuit (bank 1, sensor 2)
- P0038 Oxygen sensor heater control circuit high (bank 1, sensor 2)
- P0030 Oxygen sensor heater control circuit (bank 1, sensor 1)
- P0045 Turbocharger/supercharger boost control A circuit/open
- P0021 Intake (A) camshaft timing over-advanced or system performance (bank 2)
- P0020 Intake (A) camshaft position actuator circuit/open (bank 2)
- P0019 Crankshaft/camshaft position correlation, bank 2 sensor B (exhaust)
- P0018 Crankshaft/camshaft position correlation, bank 2 sensor A (intake)
Data: TORKO fault-code catalogue, built on OBDex (CC0-1.0) and reviewed against workshop practice. Informational only — it does not replace a diagnosis by a mechanic.
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