P20F0 SCR NOx Catalyst Over Temperature (Bank 2)

P20F0 is the bank 2 version of P20EC: the SCR catalyst in the second exhaust line has been exposed to temperatures above its permitted limit. It presupposes a V engine with one aftertreatment path per bank, which is rare; most diesels merge both banks into one SCR line and use only the bank 1 codes. No manufacturer documents P20F0 publicly. The physical background is the same as on bank 1: vanadium-based coatings degrade by sublimation above about 550 °C (Navistar patent US20190232224), and the US heavy-duty rule 40 CFR 1036.115 requires the engine design to keep the catalyst below its sublimation threshold. When only one bank overheats, the cause tends to sit on that bank, for instance a leaking injector, a misfiring cylinder or a wrong temperature sensor. Repeated events can permanently lower the bank 2 conversion (P20F2).

Likely causes

Symptoms

• Malfunction indicator lamp on
• Reduced power or interrupted regeneration to protect the catalyst

Repair estimate

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

Related codes

References: patents.google.com, law.cornell.edu.