Powertrain, generic (extended)

P28C3 EVAP System High Load Purge Line B Performance

Check engine lightOn

EmissionsRelevant

Drive cycleRequired

Limp modeNo

Under boost the intake manifold is above ambient pressure, so turbo engines add a high-load purge path: compressed air drives an ejector (venturi) that draws canister vapour into the compressor inlet, with check valves keeping boost out of the tank side. CARB requires every purge path to be checked for missing flow, from 2021 including disconnected lines, unless the high-load path carries under 1 percent of purge mass on the US06 cycle. P28C3 is the function check of a second such line, B. Line A is P04F0, used for example by Genesis on the 2.5T with a dual purge ejector that clogs with debris. No manufacturer publicly documents P28C3 or names line B. Volvo's 2019–2020 Dual Purge action shows the typical fault: a check valve upsetting ejector flow at high load, logging a code and the MIL.

Likely causes

Check valve in high-load line B sticking, leaking or fitted the wrong way round

Line B to the compressor inlet pulled off, cracked or kinked

Ejector nozzle blocked by debris or oil residue

Leak in the boost-side hose that drives the ejector

Symptoms

MIL on, usually without any change in driving behaviour
EVAP readiness not completed
Occasional fuel smell after long full-load driving

Repair estimate

DifficultyMediumDIY possible

Parts and labour€30–350

Time0.5–2 h

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

Parts involved

high load purge linepurge check valvepurge venturifuel tank pressure sensor

Related codes

P04F0 P04F1 P04AF P0496 P0497

References: law.cornell.edu, static.nhtsa.gov, static.nhtsa.gov.