P214B: SCR NOx Catalyst Inlet Temperature Too High During Particulate Filter Regeneration

What does P214B mean?

P214B is limited to the regeneration phase. To burn soot out of the particulate filter, the engine control adds late injections or uses a separate exhaust fuel injector, and the oxidation catalyst converts that fuel into heat. The code sets when the gas leaving this hot zone arrives at the SCR inlet above the limit allowed during regeneration. Navistar's patent US20190232224 describes exactly this conflict: repeated regenerations push vanadium SCR material towards its sublimation point near 550 °C, so the layout and temperature control must keep the SCR below it. No manufacturer documents P214B publicly. Compared with P214A, suspicion falls on regeneration control: a dripping exhaust injector, excess post-injection or soot burning too fast. The control unit usually aborts the regeneration.

The code tells you which monitor failed, not which part is broken. Test before replacing parts.

Symptoms

• Check engine light on, regeneration aborted
• Filter warning or rising soot load because regeneration cannot finish
• Reduced engine power

Common causes

• High Exhaust fuel injector leaking or over-dosing during regeneration
• Medium Heavily loaded filter burning off too quickly
• Medium Excess post-injection quantity from a worn engine injector
• Low Exhaust temperature sensor upstream of the SCR reading too high

Likelihood is a general estimate across vehicles; your make and model may differ.