P214F: Reductant Heater A Current Too High

P214F concerns heater A of the DEF system, which Ford and GM both assign to the heater inside the tank (heater circuit 1). The code says this element consumed more current or power than intended. Ford's 2023 diesel summary performs one check per heating cycle, right after a cold start, and decides within 2.2 s when tank heater power is higher than expected. GM's 2025 Duramax tables set P214F when heater 1 current passes 15 A in 40 consecutive 100 ms samples; that is Type A and lights the MIL after one trip; the 2015 tables detected a shorted tank heater through a conductance of at least 0.62 S, Type B. A shorted element, wet connector or chafed lead is the usual reason. Without tank heating, frozen DEF thaws late or not at all, so dosing and NOx reduction start late in winter. P21DD is the low-current counterpart.

Symptoms

• Check engine light on
• DEF system warning in cold weather
• Delayed DEF dosing after cold starts

Most likely causes

• Tank heater element internally shorted (often replaced with the tank sender unit)
• Water ingress or corrosion in the heater connector
• Chafed heater wiring shorted to ground
• Faulty heater driver in the reductant control module

What to check, in order

Start with the simplest. You can tick off each step.

1. Check the AdBlue/DEF level and quality, and do not add additives or water
2. Check the sensor's ground and make sure the signal wire is not receiving voltage from another circuit.
3. Look for white crystals around the injector and the tank
4. Check connectors and heaters with the scanner
5. Run the dosing test available on your diagnostic tool
6. Replace parts only when the test points to that component

Good to know

• Repair difficulty: medium
• It can trigger limp mode.
• It affects emissions.

What each character of P214F means

• P: Powertrain: engine and transmission
• 2: Generic code: same on every make
• 1: Air and fuel
• 4F: Specific fault in that system

Frequently asked questions

Can I keep driving with code P214F?

Deal with it soon. If the instrument cluster shows a countdown, the car may not restart once it reaches zero.

What causes code P214F?

The most common causes are: tank heater element internally shorted (often replaced with the tank sender unit); water ingress or corrosion in the heater connector; chafed heater wiring shorted to ground.

Related codes

• P21DDReductant Heater A Current Too Low
• P20B9Reductant Heater A Control Circuit/Open
• P20BAReductant Heater A Control Circuit Performance
• P20BBReductant Heater A Control Circuit Low
• P20BCReductant Heater A Control Circuit High
• P221DReductant Heater B Current Too High

Sources

• fordservicecontent.com: obd summary diesel 2023
• gsi.ext.gm.com: 25OBDG04A
• gsi.ext.gm.com: 15OBDG04 Engine Diagnostics

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.