Code result
P2256
O2 Sensor Heater Control Circuit Low Bank 1 Sensor 2
High severity
What it means
The ECU detects a low-side voltage below threshold on the heater control of the rear oxygen sensor on bank 1. The heater driver may be stuck on or shorted to ground.
Is it safe to drive?
No — stop driving
This code points to a problem that can cause damage or affect safety. Avoid driving and have the vehicle diagnosed promptly.
Most likely causes
Heater wire shorted to ground
highOne of the most commonly reported causes for this code — check this first.
Internal heater short
mediumA plausible cause — test and verify before replacing parts.
Connector pins corroded - high contact resistance
lowLess common, but worth ruling out after the more likely causes.
Related help
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