Code result
P22A4
NOx Sensor Heater Control Circuit Low
High severity
What it means
NOx Sensor Heater Control Circuit Low (Bank 1 Sensor 2): the control-circuit voltage is below the expected range. The NOx sensor heater brings the sensor to operating temperature; a fault delays accurate NOx readings used for SCR control.
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
Short to ground
highOne of the most commonly reported causes for this code — check this first.
Connector pins corroded - high contact resistance
lowLess common, but worth ruling out after the more likely causes.
Harness chafing through insulation
lowLess common, but worth ruling out after the more likely causes.
Related help
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