Powertrain, generic (extended)

P20BE Reductant Heater B Control Circuit Performance

Check engine lightOn

EmissionsRelevant

Drive cycleRequired

Limp modePossible

P20BE judges whether heater B, in most designs the heated pressure line, behaves as expected once the wiring itself checks out. GM's 2025 DEF tables flag line heater resistance below 2.80 or above 7.50 ohms, or a power error above 16.5 W, after 8 s (Type A); the 2018 tables accept a voltage-to-current ratio only between 1.51 and 3.57 ohms. Ford tests circuit 2, the pressure line heater, continuously while it heats and fails it when conductance falls below 0.3 S within 2.2 s, in addition to an on/off current and voltage comparison. For the 3.0 L EcoDiesel FCA titles the code Reductant Pressure Line Heater Control Circuit Performance; its 2014 Ram 1500 bulletin cured spurious entries with PCM software. Deutz maps P20BE to over-temperature of its pressure line heater.

Likely causes

Pressure line heating wire degraded, resistance outside the window

High-resistance joint at the line heater connector

Engine control software setting the code erroneously (FCA 18-028-14)

Low heater supply voltage distorting the current measurement

Symptoms

Malfunction indicator lamp after a heating phase
Ice in the pressure line on cold starts, dosing late
Possible NOx efficiency codes as a consequence

Repair estimate

DifficultyMediumWorkshop job

Parts and labour€0–800

Time0.5–3 h

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

Parts involved

reductant line heater b

References: fordservicecontent.com, gsi.ext.gm.com, gsi.ext.gm.com, static.nhtsa.gov.