P24EA
- Powertrain
- Manufacturer-specific
- Emissions
Diagnose soon
Usually safe to drive short distances, but the fault will not clear itself and can worsen or fail an emissions test.
NH3 Sensor Supply Voltage Circuit
This code is in our catalogue but has not yet been through editorial review, so the guidance below is limited to what our structured data supports. We publish deeper diagnostic content only after a code has been reviewed — here is why.
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.
A trouble code records what a control module measured. It does not identify which part failed. Test before replacing anything.
- Safe to drive
- Usually safe to drive short distances, but the fault will not clear itself and can worsen or fail an emissions test.
- Urgency
- Diagnose soon
- Will it pass emissions
- No
- Check engine light
- Solid
| # | Cause | How often | Component |
|---|---|---|---|
| 1 | Open or shorted supply wire | Very common | — |
| 2 | Failing supply rail inside the dosing module | Common | — |
Ordering reflects how often each cause is responsible in general, not a probability for your vehicle. Confirm by testing.
- Nh3 Sensor
- Supply Wiring
- Dosing Module
- Definition
- Generic code set (SAE J2012 / ISO 15031-6) via the OBDexopen database, dedicated to the public domain under CC0-1.0.
- Diagnostic guidance
- Written and reviewed in-house. See our editorial policy.
- Review status
- Awaiting review
Found something wrong? Tell us — we publish corrections.