P24E6
NH3 Sensor Heater Circuit/Open
What it means
The heater inside the ammonia (NH3) slip sensor warms the sensing cell to operating temperature so it can read tailpipe ammonia. The ECM detects an open in the heater control circuit — no current flows when the heater should be active, so the sensor never reaches its working point and SCR closed-loop control is suspended.
Is it safe to drive?
The vehicle is usually drivable for short distances, but the problem can worsen or affect emissions. Diagnose and repair as soon as practical.
Most likely causes
Burnt-out heater winding inside the sensor
highOne of the most commonly reported causes for this code — check this first.
Broken wire or unplugged connector
mediumA plausible cause — test and verify before replacing parts.
Failed heater driver stage in the dosing module
lowLess common, but worth ruling out after the more likely causes.
Related help
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