P0037: HO2S heater control circuit low (bank 1, sensor 2)
An OBD-II trouble code meaning the heater control circuit of oxygen sensor 2 on bank 1 is reading lower than the engine computer expects.
How to read it
P0037 is one of the standard OBD-II trouble codes stored when the check engine light comes on. SAE J2012, the standard that defines the codes, names it “HO2S Heater Control Circuit Low Bank 1 Sensor 2”; Volkswagen’s service information gives the same name.
Also searched as: code P0037, P0037 code.
Code names follow SAE J2012. Manufacturers add codes of their own, and the same code can have several causes: the vehicle’s service information or a qualified mechanic can say what it means for a particular car.
What the monitor checks
The federal rule requires the system to detect oxygen sensor deterioration or malfunction that raises emissions to 1.5 times the standard.
What the manual says to do
Ford’s F-150 manual says that if the indicator stays on, the vehicle should be serviced at the first available opportunity, and that continued driving with it on can mean higher emissions, lower fuel economy, rougher running and more costly repairs.
How the light goes out
Under the federal rule, the check engine light may go out once the fault has not come back during three trips in a row in which its monitor runs without finding it. The system may erase the stored code if the same code has not been registered again in at least 40 engine warm-up cycles.
More OBD-II trouble codes
- P0420: Catalyst system efficiency below threshold (bank 1)
- P0430: Catalyst system efficiency below threshold (bank 2)
- P0300: Random/multiple cylinder misfire detected
- P0301: Cylinder 1 misfire detected
- P0302: Cylinder 2 misfire detected
- P0303: Cylinder 3 misfire detected
- P0304: Cylinder 4 misfire detected
- P0305: Cylinder 5 misfire detected
Sources
- SAE J2012: Diagnostic Trouble Code Definitions (2002), SAE J2012, April 2002 (technically equivalent to ISO/DIS 15031-6), SAE International; published by Public.Resource.Org on the Internet Archive, Appendix B (powertrain DTCs)
- 2014 Volkswagen CC Quick Reference Specification Book, February 2014, Volkswagen of America; published by NHTSA, DTC chart
- 40 CFR 86.1806-05, On-board diagnostics (2012 edition), 40 CFR 86.1806-05, US Government Publishing Office (Code of Federal Regulations), § 86.1806-05(b) and (c)
- 2020 F-150 Owner's Manual, Ford Motor Company, Instrument Cluster; On-Board Diagnostics (OBD-II)
Last reviewed September 28, 2026 by Rory Hansen. How we research