P24FF: Reductant Temperature Too High

What it means

The reductant temperature is above the expected limit. The code does not identify the cause of the high temperature.

At a glance

• Usually lights the check-engine light
• Affects emissions; the car can fail an emissions test

How it works

The reductant system stores and supplies fluid such as DEF or AdBlue for SCR emissions control. P24FF means the measured reductant temperature is above the expected limit; the code does not establish whether the tank heater, exhaust heat, or another condition caused it.

Common causes

Most likely first.

1. Tank heater stuck on
2. Heat soak from exhaust or engine bay

Symptoms

• Check engine light or NOx warning on
• AdBlue/DEF level or quality warning
• Possible no-start countdown after ignore period
• Failed emissions inspection (NOx)

How to diagnose it

1. Record freeze-frame data and compare the reported reductant temperature with ambient conditions and any available tank-temperature readings.
2. Inspect the tank, temperature sensor wiring, and nearby harness for heat exposure, damage, or poor connections.
3. Check whether the tank heater is being commanded on when it should be off, using scan-tool data and the manufacturer's procedure.
4. Verify the temperature sensor reading and heater circuit against the manufacturer's specifications.
5. If the sensor and heater circuit test correctly, inspect for abnormal heat transfer from the exhaust or engine bay to the reductant tank.

Common fixes

• Repair damaged temperature-sensor wiring or connector terminals.
• Replace a faulty reductant temperature sensor if confirmed by testing.
• Repair or replace a tank heater that remains energized when not commanded.
• Restore damaged heat shielding or correct the source of excessive heat exposure.

Can I keep driving?

Avoid long trips if a reductant or NOx warning is active, because emissions control may be limited and some vehicles can start a no-start countdown. Follow the dashboard instructions and address the warning promptly.