These are code references, not a list of confirmed faults on every vehicle. Read the source and applicability notes, then match the exact vehicle, year, engine and scan report.

Exhaust pressure offset is compared with ambient pressure after shutdown

Exhaust-pressure low-circuit evidence must retain the source’s labeling caveat

A high exhaust-pressure circuit signal is separate from real overpressure

An erratic exhaust-pressure code can be a model disagreement

exhaust throttle open circuit with an off-state driver

exhaust throttle position-tracking performance

exhaust throttle command short-to-ground detection

exhaust throttle command circuit short to power

Exhaust Pressure Control Valve A Intermittent

Exhaust Pressure Sensor B Circuit

Exhaust Pressure Sensor B Circuit Range/Performance

Exhaust Pressure Sensor B Circuit Low

Exhaust Pressure Sensor B Circuit High

Exhaust Pressure Sensor B Circuit Intermittent/Erratic

exhaust-flap binding can remain after an ECU update

Fan 1 relay-control opening detected with the driver off

Fan relay channel two reports an electrical command mismatch

The third fan relay output has its own feedback check

Fan performance uses weighted command-following evidence

Fan Circuit Current High

Fan Power/Ground Circuit

Volkswagen CJAA low-pressure EGR position-sensor circuit

Ford 6.0L EGR throttle actuator circuit fault

Ford throttle open-position learning is outside its limits

high-pressure EGR short-to-ground current signature

exhaust throttle fails its spring-return position check

Volkswagen CJAA exhaust-flap position signal low

Volkswagen CJAA exhaust-flap closed-position learning

exhaust throttle SENT position feedback below range

exhaust throttle position signal above its raw upper limit

Exhaust Pressure Control Valve A Position Sensor/Switch Circuit Intermittent/Erratic

high-pressure EGR command short to the power supply

bank 1 secondary-air flow can fail at several points

bank 2 secondary-air flow and the paired-code clue

Fan Overspeed

Measured cooling-fan speed falls short of a modeled response

Fan speed high is judged against an estimated limit

Tank vacuum develops even though purge is commanded closed

EVAP purge-flow assessment from tank-pressure response

EVAP vent circuit low is a power-stage grounding report

EVAP vent circuit high reflects a short-to-battery status

EGR B Flow

insufficient low-pressure EGR in the air-flow model

excessive low-pressure EGR inferred from fresh-air mismatch

high-pressure EGR closed-stop learning is outside its window

low-pressure EGR endpoint learning exceeds permitted limits

Exhaust Pressure Control Valve B

Exhaust Pressure Control Valve B Range/Performance

Exhaust Pressure Control Valve B Low

Exhaust Pressure Control Valve B High

Exhaust Pressure Control Valve B Intermittent

Exhaust Pressure Control Valve B Stuck Open

Exhaust Pressure Control Valve B Stuck Closed

Exhaust Pressure Control Valve B Position Sensor/Switch Circuit

Exhaust Pressure Control Valve B Position Sensor/Switch Circuit Range/Performance

Exhaust Pressure Control Valve B Position Sensor/Switch Circuit Low

Exhaust Pressure Control Valve B Position Sensor/Switch Circuit High

Exhaust Pressure Control Valve B Position Sensor/Switch Circuit Intermittent/Erratic

Purge valve B open-load detection uses a voltage window

Purge valve B low is an off-state driver-voltage fault

Purge valve B high is detected from energized-driver current

bank-2 purge valve tested through a commanded pressure change

EVAP System Purge Control Valve B Stuck Closed

Refueling Vapor Control Valve Circuit/Open

Refueling Vapor Control Valve Circuit Low

Refueling Vapor Control Valve Circuit High

Refueling Vapor Control Valve Stuck Performance/Stuck Open

Refueling Vapor Control Valve Stuck Closed

F-150 PowerBoost fuel-door latch checks before deeper diagnosis

Cherokee stored fuel-door fault and false-setting logic

Fuel Fill Door Position Sensor/Switch Circuit Intermittent/Erratic

fuel-door position has entered an invalid signal band

fuel-door position feedback is below its allowed range

fuel-door position feedback is above the calibrated limit

fuel-door lock driver reports an electrical fault

the commanded fuel-door lock transition did not occur

Fuel Fill Door Lock Control Circuit Low

Fuel Fill Door Lock Control Circuit High

Fuel Fill Door Unlock Control Circuit/Open

fuel-door unlocking failed to produce the expected transition