What Does P0037 Mean?
The ECM has detected a low voltage condition in the heater circuit of the Bank 1, Sensor 2 (downstream) heated oxygen sensor. The heater circuit voltage is below the expected threshold, suggesting a short to ground or excessively low heater resistance. This affects the sensor's ability to quickly reach operating temperature for accurate catalyst monitoring.
Common Causes
30%
Heater element resistance too low (partially shorted O2 sensor)
30%
Heater circuit wiring shorted to ground
20%
Corroded or water-damaged sensor connector
10%
Low system voltage affecting heater circuit monitoring
10%
ECM heater driver fault pulling the circuit low
Diagnostic Steps
1
Check system voltage with engine running — should be 13.5–14.7V. A weak battery or failing alternator can trigger false low-voltage heater codes across multiple sensors.
2
Disconnect the B1S2 O2 sensor connector and measure heater resistance — expect 2–15 ohms. A reading significantly below spec indicates a partially shorted heater that needs sensor replacement.
3
With the sensor disconnected, measure voltage on the control wire. If voltage rises to normal, the sensor was pulling it low. If it remains low, the harness has a short to ground.
4
Inspect the downstream O2 sensor wiring for damage from road debris, undercarriage contact, or exhaust heat. The Sensor 2 location is particularly vulnerable to physical damage and water splash.
5
Check each heater terminal to the sensor body for insulation breakdown — readings below 10k ohms indicate an internal short to ground in the sensor.
Estimated Repair Cost
$80 - $300
Parts + labor, varies by vehicle and location
The ECM has detected a low voltage condition in the heater circuit of the Bank 1, Sensor 2 (downstream) heated oxygen sensor. The heater circuit voltage is below the expected threshold, suggesting a short to ground or excessively low heater resistance. This affects the sensor's ability to quickly re...
The most common cause of P0037 (Heated Oxygen Sensor (HO2S) Heater Circuit Low Voltage Bank 1 Sensor 2) is: Heater element resistance too low (partially shorted O2 sensor)
Typical repair costs for P0037 range from $80 to $300, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to drive. This sensor monitors catalyst efficiency rather than controlling fuel trim. No drivability symptoms expected. The primary concern is emissions compliance and potential failure of an emissions inspection.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0037 to identify the root cause.
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Quick Info
Category
Powertrain
System
Fuel System / Emissions
Difficulty
Type
Generic (SAE)
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