P0051 HO2S Heater Control Circuit Low Bank 2 Sensor 1

P0051 indicates a low heater-control circuit condition for bank 2 sensor 1. The upstream heater circuit is lower than the module expects.

Code status

Needs verification

Not yet verified against SAE J2012_202509 / J2012DA. Treat unverified rows as a lookup aid, not repair authority.

System
Fuel / Air
Scope
iso-sae-controlled-p0
Standard
SAE J2012 / ISO 15031-6
Source
legacy-import

Diagnostic boundary

A diagnostic trouble code reports that a monitored test failed. It does not prove one specific part is bad, and manufacturer logic can add vehicle-specific conditions.

Do not replace the oxygen sensor until the low-circuit condition is separated from wiring, fuse, relay, or driver-control faults.

Useful checks before replacing parts

Related OBD-II codes

These nearby fuel / air entries can help compare wording and fault area. They may share the same verification status as the source database.