DOCUMENTED DIAGNOSTIC CONTEXT

Diagnostic code articles — Page 31.

Understand what the recorded fault means, which findings change the diagnosis, and what the cited documentation can confirm. Each article states the system or vehicle scope it covers.

Some sources leave details unresolved. Those articles include a visible source note; a code match alone does not establish applicability to your vehicle.

Cylinder 2 ignition control is diagnosed electrically low

Cylinder 2 ignition output remains high in the monitored on state

Cylinder 2 ion-sensor signal error at lower engine speed

Cylinder 3 ignition control has a ground-short signature

Cylinder 3 ignition control fails its high-circuit check

Cylinder 3 ion-sensor input error and the P0303 decision

A coil low-circuit fault with an unresolved channel label

Why a coil high-circuit code needs a verified channel mapping

Cylinder 4 secondary-ignition code interpreted through ion sensing

Why a low ignition-driver signal needs its command state

Interpreting an ignition output that stays high when commanded on

Separating ignition circuit low from a combustion misfire

Why ignition-driver high is judged during an on command

Understanding the coil G off-state low-voltage check

Coil G circuit high and the significance of the active command

A low ignition-control signal with an unresolved coil label

Reading an ignition circuit-high code without guessing the cylinder

Coil-driver low evidence depends on ignition architecture

fuel metering valve 2 open-load detection

fuel metering valve 2 low-side short to ground

fuel metering valve 2 low-side short to power

A low regulator supply circuit can create a high voltage drop across its driver

A regulator supply-high fault is assessed across an off-state driver

EGR sensor internal status must be separated from lost communication

low-pressure EGR differential-pressure signal high

low-pressure EGR differential-pressure signal low

EGR differential-pressure offset is implausible at key-off

EGR differential-pressure signal changes too quickly

NOx sensor oxygen reading too high during diesel deceleration

How pressure pulsations expose a stuck turbo bypass valve

NOx sensor 3 internal current control is unstable

NOx sensor 3 reports below the lower concentration limit

NOx sensor 3 exceeds the upper concentration range

open heater-control circuit at NOx sensor 3

NOx sensor 3 heater control is shorted low

NOx sensor 3 heater control is shorted high

NOx sensor 3 heater-resistance sensing circuit is open

NOx sensor 3 heater resistance misses its target

NOx sensor 3 supply voltage is below range

NOx sensor 3 heater-sense path shorted to ground

NOx sensor 3 heater-sense path shorted to power

NOx sensor 3 sensing cavities fail an afterrun self-test

coolant bypass valve C digital position signal low

coolant bypass valve C digital position signal high

coolant bypass valve C motor driver overcurrent

EVAP leak-detection pump control circuit is diagnosed open

EVAP leak-detection pump output has a low-circuit fault

EVAP pump driver detects unwanted power during its on command

low leak-pump sense feedback must persist in Audi's CTUA monitor

leak-pump feedback depends on vacuum, power and purge sealing

Volkswagen EVAP pump-current instability

Volkswagen leak-detection pump heater open-circuit monitor

Volkswagen leak-detection pump heater control low

Volkswagen leak-detection pump heater high-current classification

EGR slow response is evaluated using changing air-mass targets

Volkswagen CJAA EGR and fuel-adaptation limits

front oxygen-signal limits depend on the selected gain characteristic

bank 2 front-oxygen feedback exceeds the CTUA signal-range criterion

EVAP switching-valve control circuit has an open signature

EVAP switching-valve circuit-low row contains conflicting fault wording

low-pressure EGR cooler efficiency below its threshold

EVAP switching-valve driver detects a short to power

Sportage vent restriction after the valve tests correctly

An EGR cooling-valve open-load report is an actuator-circuit finding

A low EGR cooling-valve circuit is distinct from an open-load fault

A high EGR cooling-valve circuit needs its own electrical evidence

exhaust protection checks both temperatures and temperature differences

Ford exhaust-temperature sensor 3 model-plausibility fault

exhaust temperature sensor 3 fails to respond after a soak

exhaust temperature sensor 3 below its electrical range

exhaust temperature sensor 3 above its electrical range

exhaust temperature sensor 3 changes implausibly fast

DPF restriction and software must match the installed filter generation

AIR pressure can be stuck inside its electrical range

secondary-air pressure is compared before engine cranking

Low secondary-air pressure signal and why the voltage matters

High secondary-air pressure signal is not proof of high airflow

Bank 2 AIR pressure can fail while staying within range

Bank 2 AIR pressure rationality depends on pump state

Bank 2 AIR pressure low voltage relative to its reference