P0051Low SeverityEmissions

HO2S Heater Circuit Low (Bank 2, Sensor 1)

What This Means

The upstream oxygen sensor heater on bank 2 is reading low voltage. A short to ground is preventing the heater from warming the sensor properly.

Common Symptoms

Check engine light on
Slightly rich running cold
Higher emissions
Emissions test failure

Common Causes

Short to ground in wiring
Failed heater element
Corroded connector
Damaged harness
Ground fault

Estimated Repair Cost

$100 – $400

Parts and labor (varies by vehicle and location)

Difficulty:Easy

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For informational purposes only. Diagnostic trouble codes are starting points for diagnosis, not definitive answers. Always consult a certified mechanic for proper diagnosis and repair. Estimated costs vary by vehicle, location, and shop rates.