Code result
P24E9
NH3 Sensor Heater Circuit Performance
Moderate severity
What it means
The heater of the NH3 slip sensor is electrically intact, but the warm-up profile or steady-state temperature feedback does not match the ECM model. The sensor takes too long to reach operating temperature or drifts away from setpoint, so SCR closed-loop control is delayed or held off.
Is it safe to drive?
Use caution
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
Aged heater with increased resistance
highOne of the most commonly reported causes for this code — check this first.
Poor thermal contact between heater and sensing cell
mediumA plausible cause — test and verify before replacing parts.
Related help
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