Reductant Heater A Performance
There’s an issue with the performance of the reductant heater.
Heads up: this code wasn't in our hand-written library yet, so DiagCoach AI built this page on the fly. Double-check critical specs against service info before condemning parts.
What it means (plain English)
The reductant heater warms up the diesel exhaust fluid (DEF) so it can work properly in lower temperatures. If it’s not working right, it means the fluid might freeze or not spray correctly, leading to increased emissions.
What the computer is actually seeing
The engine control module (ECM) monitors the temperature and voltage signals from the reductant heater. It expects the voltage to be around 12V when operational and specific temperature readings that correlate with DEF fluid freezing point.
What a healthy reading looks like
Heater should show around 12V, and the temperature of the DEF should be above 11°F (-12°C) when the engine is running.
Guided diagnostic — the DiagCoach way
Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.
- 1Check the DEF fluid level—should be above the minimum mark. If low, refill and clear the code to retest.
- 2Inspect the wiring and connectors at the reductant heater for any damage or corrosion. Repair as needed.
- 3Measure the voltage at the heater connector while the engine is running; it should be about 12V. If not, check power and ground circuits.
- 4Test the reductant heater itself for resistance. You should see a resistance value typically between 10 to 20 ohms. If it’s open or shorted, replace the heater.
Common causes
- Faulty reductant heater
- Bad wiring or connectors to the heater
- Damaged DEF lines
- Low DEF fluid level
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
You can drive safely, but emissions may be higher and you might notice reduced performance, especially in cold temperatures.
Will this code come back after clearing it?
It may return if the underlying issue is not fixed, like a bad heater or wiring problem.
Why does this code appear alongside others like P20C0?
They often show together due to shared wiring or system components. A fault in one can affect the others.
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