Code result
P24EA
NH3 Sensor Supply Voltage Circuit
Moderate severity
What it means
The supply rail that powers the NH3 slip sensor electronics (typically 5 V or 12 V from the dosing/SCR module) is out of tolerance. Without a stable supply the sensor cannot deliver a valid ammonia reading, and the ECM disables the closed-loop SCR strategy.
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
Open or shorted supply wire
highOne of the most commonly reported causes for this code — check this first.
Failing supply rail inside the dosing module
mediumA plausible cause — test and verify before replacing parts.
Related help
Get the full diagnosis
Add your vehicle and see step-by-step repair help, recalls, and TSBs in Wrenchify.
Diagnose P24EA freeNo credit card required