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All codes/P24E5

P24E5

NH3 Sensor Circuit Intermittent/Erratic

Moderate severity

The ammonia (NH3) slip sensor downstream of the SCR catalyst delivers an intermittent or erratic signal. The ECM expects a smooth voltage proportional to ammonia concentration in the tailpipe — sudden jumps, dropouts or noise mean the wiring, connector or sensing element is failing. Used to close-loop the AdBlue/DEF dosing strategy.

The ammonia (NH3) slip sensor downstream of the SCR catalyst delivers an intermittent or erratic signal. The ECM expects a smooth voltage proportional to ammonia concentration in the tailpipe — sudden jumps, dropouts or noise mean the wiring, connector or sensing element is failing. Used to close-loop the AdBlue/DEF dosing strategy.

Common causes

  • Corroded or loose sensor connector

    One of the most commonly reported causes for this code — check this first.

    high

    Typical part cost: $200-990

  • Chafed or vibrating harness near the exhaust

    A plausible cause — test and verify before replacing parts.

    medium

    Typical part cost: $200-990

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First things to check

  1. 1Confirm the code with a scan tool and check for additional related codes.
  2. 2Inspect the relevant sensors, wiring, and connectors for damage or corrosion.

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Tools you may need

Already have a compatible scanner? Use it. If not, a Bluetooth OBD2 adapter can help you confirm engine codes and check supported live sensor data before replacing parts.

Illustration of a Bluetooth OBD2 adapter, not a product photo

Basic checks

Veepeak OBDCheck BLE

A Bluetooth LE adapter for reading standard engine codes and supported live data.

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Illustration of a Bluetooth OBD2 adapter, not a product photo

Regular diagnostics

vgate iCar Pro BLE 4.0

A Bluetooth LE adapter with an automatic sleep feature for routine code and sensor checks.

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Illustration of a Bluetooth OBD2 adapter, not a product photo

Another option

OBDLink CX

A Bluetooth LE adapter to consider when comparing supported vehicles and diagnostic apps.

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Illustrations shown, not product photos. Check vehicle, phone and app compatibility before buying. These adapters do not guarantee access to ABS, airbags or manufacturer-specific systems. Clearing a code does not repair the fault and can reset emissions readiness monitors.

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Related codes

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Frequently asked questions

What does P24E5 mean?

P24E5 means "NH3 Sensor Circuit Intermittent/Erratic". It is a generic OBD-II code that points to a fault in the evaporative / emission control system.

What are the most common causes of P24E5?

corroded or loose sensor connector; chafed or vibrating harness near the exhaust; aged ceramic sensor element drifting under heat cycles — these are the most commonly reported causes. Verify with a proper diagnosis before replacing parts, or use the Wrenchify app for a vehicle-specific diagnosis.

Can I keep driving with this code?

The vehicle is usually drivable for short distances, but the problem can worsen or affect emissions. Diagnose and repair as soon as practical. Use the Wrenchify app for a full diagnosis specific to your vehicle.

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