P0037: HO2S Heater Control Circuit Low (Bank 1 Sensor 2)
Quick Answer
Safe to drive (short-term)
P0037 means the engine computer measured too little current or too low a voltage in the heater circuit of the downstream oxygen sensor on bank 1, the one after the catalytic converter. That is what a burned-out heater, a blown fuse or a broken supply wire produces. The sensor only checks the converter, so the car usually drives exactly as before. A new downstream sensor typically costs about 110 to 270 EUR fitted.
- Severity
- Low · Emissions
- Estimated repair cost
- From €1 to €370+, varies by vehicle
€1 or €370, depending on your car.
- Replace O2 sensor heater fuse€1–€3
- Replace downstream O2 sensor (OEM quality)€140–€370
A scan shows whether P0037 is really stored on your car, which codes sit next to it and how urgent each one is.
A scan needs a Bluetooth OBD2 adapter (Bluetooth LE on iPhone), about €25-60; the built-in demo runs without one. See which adapter to buy
What does P0037 mean?
P0037 is a emissions-related diagnostic trouble code classified as low severity.
Where it is on the car
- Engine
- Oxygen sensor before the converter (sensor 1)
- Catalytic converter
- Oxygen sensor after the converter (sensor 2, or 3 on some cars)
- Silencer and tailpipe
This code is about the sensor's heater, which warms it up after a cold start. The usual causes are a blown fuse, a damaged connector or wire, or a worn-out heater inside the sensor. On some cars this sensor is an air-fuel ratio sensor, which sits in the same place.
What are the symptoms of P0037?
- Check engine light on, usually with no change in how the car drives
- No noticeable effect on power or fuel economy in most cars
- Catalyst monitor slow to complete, or incomplete after the code is cleared
- Oxygen sensor heater readiness monitor incomplete after the code is cleared
- Possible rejection at an emissions inspection while the warning light is on
What causes P0037?
Burned-out (open) heater element inside the downstream oxygen sensor (normal wear with age and heat)
: high
Blown heater fuse, often shared with other sensor heaters so several heater codes appear together
: medium
Corroded or damaged connector or wiring under the car, exposed to water, salt and road debris
: medium
Faulty heater relay or power supply feeding the sensor heater
: low
Control wire shorted to ground, or a faulty heater driver in the engine computer (rare)
: low
Is it safe to drive with P0037?
Generally yes, for short-term driving. Safe to drive. The sensor after the catalytic converter only checks how well the converter works; it does not set the fuel mixture, so the engine runs as before. Without its heater the sensor takes longer to warm up and the converter check may not complete. Fix it promptly: the warning light hides any new fault and can get the car rejected at an emissions inspection.
How do you diagnose P0037?
- Read all stored codes and freeze frame. P0037 together with P0031, P0057 or other heater codes points to a shared fuse, relay or supply wire rather than several failed sensors
- Check the oxygen sensor heater fuse named in the owner's manual or on the fuse box lid. Replace it if blown, and if it blows again look for a short in the heater or its wiring
- Raise the car safely, unplug the Bank 1 Sensor 2 connector and measure the resistance across the two heater pins. Many downstream sensors read between about 3 and 15 ohms at room temperature; check your car's specification. An open circuit means the heater has burned out
- With the key on, check for battery voltage on the heater supply pin on the harness side of the connector. No voltage points to the fuse, relay or supply wire
- Inspect the connector and the wiring along the exhaust and underbody for corrosion, pushed-back pins, melted insulation or chafing, and repair as needed
- After the repair, clear the code and drive a mix of town and steady faster driving. With a generic OBD2 reader, check that the oxygen sensor heater and catalyst readiness monitors complete before an inspection
How much does P0037 cost to fix?
| Repair | Parts Cost | Labor Cost | Total Estimate | DIY Difficulty |
|---|---|---|---|---|
| Replace O2 sensor heater fuse | €1–€3 | €0–€0 | €1–€3 | Easy |
| Replace O2 sensor heater relay | €10–€40 | €20–€60 | €30–€100 | Easy |
| Repair wiring or connector | €5–€20 | €40–€120 | €45–€140 | Moderate |
| Replace downstream O2 sensor (Bank 1) | €50–€150 | €60–€120 | €110–€270 | Moderate |
| Replace downstream O2 sensor (OEM quality) | €80–€250 | €60–€120 | €140–€370 | Moderate |
Prices estimated as of October 2026. Costs vary by region, vehicle, and shop.
P0037 in the Skanyx app: what real cars show
Counts from fault-code scans in the Skanyx app in the 12 months to October 2026: 17 of the 806 cars that stored at least one code had P0037 stored.
One car counts once, however often it was scanned. Figures below 15 cars are not shown. This is the fleet of one app's users, mostly in Europe, not a survey of the whole market.
P0037 on specific vehicles
P0037 on Nissan
Nissan Juke (HR16DE/MR16DDT) · Nissan 350Z (VQ35HR)
Related diagnostic codes
Common questions about P0037
- What does code P0037 mean?
- P0037 means the heater circuit of the Bank 1 Sensor 2 oxygen sensor (after the catalytic converter, on the side of the engine with cylinder 1) is reading low: too little current or too low a voltage. Usually the heater has burned out or lost its power supply.
- Is P0037 serious?
- No. The downstream sensor does not control the fuel mixture, so the engine runs normally and fuel use barely changes. The catalyst check may not complete, and the warning light can get the car rejected at an emissions inspection (rules vary by country), so fix it before the next inspection.
- Can a blown fuse cause P0037?
- Yes. With the fuse blown the heater has no power, so the circuit reads low. On many cars the same fuse feeds other oxygen sensor heaters, so P0037 appearing with P0031 or P0057 is a strong hint to check the fuse first.
- Where is the bank 1 sensor 2 oxygen sensor?
- It is threaded into the exhaust just after the catalytic converter on the bank with cylinder 1. On a four-cylinder engine there is only one bank, so it is simply the sensor after the converter. It is usually reached from under the car.
- How much does it cost to fix P0037?
- A blown fuse costs 1 to 3 EUR. A heater relay costs about 30 to 100 EUR fitted, and a wiring or connector repair about 45 to 140 EUR. A new downstream oxygen sensor costs roughly 110 to 270 EUR fitted, or 140 to 370 EUR with an OEM-quality sensor.
- Can a generic OBD2 scanner diagnose P0037?
- A generic OBD2 reader shows the code, its freeze frame, the downstream sensor voltage and the readiness monitors, including the oxygen sensor heater and catalyst monitors. It cannot show heater current, heater duty cycle or the manufacturer's heater adaptation values; those need the brand's own diagnostic software.
Read our detailed guides
Sources
- nijutech.com nijutech.com/p0037_p0038_ho2s2_heater-861.html
- nijutech.com nijutech.com/p0037_p0038_ho2s2_heater-725.html
- en.wikipedia.org en.wikipedia.org/wiki/Nissan_Juke
- 350z.se 350z.se/fsm/coupe/2007/ec.pdf
- en.wikipedia.org en.wikipedia.org/wiki/Nissan_350Z