THE CODE DIRECTORY

Diagnostic code references — Page 72.

Browse canonical reference entries. Each definition keeps its own source and vehicle-applicability limits.

Generic OBD-II

P20C0

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.

A DEF line-heater short-to-power report and its diagnostic shutdown

heater C maps to the second tank heater in this system

Checking the second DEF tank heater’s resistance and power performance

Locating the meaning of a low circuit on the second DEF tank heater

heater 3 short-to-power is confirmed with heating switched off

Reductant Heater D Control Circuit/Open

Reductant Heater D Control Circuit Performance

Reductant Heater D Control Circuit Low

Reductant Heater D Control Circuit High

Reductant Control Module Requested MIL Illumination

Reductant Injection Air Pressure Leakage

The exhaust fuel injector’s open check uses different driver states

aftertreatment injector performance is judged through exhaust heat

A low aftertreatment-injector circuit result has separate recovery logic

A high exhaust injector circuit can be reported through on-state overcurrent

Exhaust Aftertreatment Fuel Injector A Stuck Open

Exhaust Aftertreatment Fuel Injector A Stuck Closed

Exhaust Aftertreatment Fuel Injector B Control Circuit/Open

Exhaust Aftertreatment Fuel Injector B Control Performance

Exhaust Aftertreatment Fuel Injector B Control Circuit Low

Exhaust Aftertreatment Fuel Injector B Control Circuit High

Exhaust Aftertreatment Fuel Injector B Stuck Open

Exhaust Aftertreatment Fuel Injector B Stuck Closed

Exhaust Aftertreatment Fuel Supply Control Circuit/Open

Volkswagen CJAA aftertreatment fuel-control deviation

Exhaust Aftertreatment Fuel Supply Control Circuit Low

Exhaust Aftertreatment Fuel Supply Control Circuit High

Exhaust Aftertreatment Fuel Supply Control Stuck Open

Exhaust Aftertreatment Fuel Supply Control Stuck Closed

Exhaust Aftertreatment Fuel Pressure Sensor Circuit

Exhaust Aftertreatment Fuel Pressure Sensor Circuit Range/Performance

Exhaust Aftertreatment Fuel Pressure Sensor Circuit Low

Exhaust Aftertreatment Fuel Pressure Sensor Circuit High

Exhaust Aftertreatment Fuel Pressure Sensor Circuit Intermittent/Erratic

exhaust temperature sensors are compared after a long soak

Exhaust Gas Temperature Sensor 1/3 Correlation Bank 1

particulate-filter temperature correlation uses startup references

Exhaust Gas Temperature Sensor 1/2 Correlation Bank 2

Reductant Injection Air Pressure Too Low

Reductant Injection Air Pressure Too High

When DEF pressure fails to follow the commanded setpoint

reductant pressure exceeds its current target

Reductant Control Module Power Relay De-Energized Performance - Too Early

Reductant Control Module Power Relay De-Energized Performance - Too Late

SCR NOx Catalyst - Over Temperature Bank 1

SCR NOx Pre-Catalyst - Over Temperature Bank 1

SCR efficiency is a filtered model-based judgment

SCR NOx Pre- Catalyst Efficiency Below Threshold Bank 1

SCR NOx Catalyst - Over Temperature Bank 2

SCR NOx Pre-Catalyst - Over Temperature Bank 2

SCR NOx Catalyst Efficiency Below Threshold Bank 2

SCR NOx Pre- Catalyst Efficiency Below Threshold Bank 2

Reductant Consumption Too Low

Reductant Consumption Too High

Reductant Injection Valve Stuck Open Bank 1 Unit 1

Reductant Injection Valve Stuck Open Bank 2 Unit 1

swirl-flap position does not track a settled command

Intake Manifold Runner Control Circuit Performance Bank 2

Reductant Pump B Control Circuit/Open

Reductant Pump B Control Performance/Stuck Off

Reductant Pump B Control Circuit Low

Reductant Pump B Control Circuit High

first DEF injector needs excessive delivery compensation

reductant-controller performance includes memory and calibration checks

Why a throttle motor circuit-open code can include driver overheating

Throttle position differs from its modeled response

throttle motor driver reports a short-to-ground condition

throttle driver short-to-power differs from a position error

Mazda diesel idle-control diagnosis includes boost and vacuum faults

throttle shutdown-path monitoring refers to the previous cycle

limited power is a throttle-system response, not a single-part diagnosis

Throttle processor communication is distinct from a plate stuck in position

throttle module performance covers internal integrity tests

Learned throttle minimum position outside the permitted window

The bank 2 throttle circuit code has separate open-load and thermal paths

Throttle tracking error with a tolerance that changes as the command moves

Throttle Actuator B Control Motor Circuit Low

Throttle Actuator B Control Motor Circuit High

Throttle/Pedal Position Sensor/Switch C/F Voltage Correlation

Throttle Actuator B Control System - Forced Limited RPM