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.

Direct Ozone Reduction Catalyst Temperature Sensor Circuit High

Direct Ozone Reduction Catalyst Temperature Sensor Circuit Intermittent/Erratic

Direct Ozone Reduction Catalyst Deterioration Sensor Circuit

Direct Ozone Reduction Catalyst Deterioration Sensor Circuit Range/Performance

Direct Ozone Reduction Catalyst Deterioration Sensor Circuit Low

Direct Ozone Reduction Catalyst Deterioration Sensor Circuit High

Direct Ozone Reduction Catalyst Deterioration Sensor Circuit Intermittent/Erratic

Direct Ozone Reduction Catalyst Efficiency Below Threshold

Supercharger clutch command and rotation disagree

Turbo-speed plausibility is a difference test, not overspeed

Vacuum Reservoir Control Circuit/Open

Vacuum Reservoir Control Circuit Low

Vacuum Reservoir Control Circuit High

Hood-switch signal falls into an invalid intermediate range

Hood-switch signal is below the configured lower limit

Hood-switch input exceeds its configured electrical range

A turbo-speed input stuck low must also lack pulse progress

What a high turbo-speed line means when pulses stop changing

Turbocharger/Supercharger Speed Sensor A Circuit Intermittent

Cruise Control Front Distance Range Sensor Single Sensor or Center

Fuel Additive Control Module Requested MIL Illumination

Fuel Additive Control Module Warning Lamp Request

Turbocharger Boost Control Position Sensor B Circuit

Turbocharger Boost Control Position Sensor B Circuit Range/Performance

Turbocharger Boost Control Position Sensor B Circuit Low

Turbocharger Boost Control Position Sensor B Circuit High

Open brake-vacuum pump control circuit in a limited GM application

Ram eTorque vacuum-pump performance and calibration

Low vacuum-pump control circuit is a driver-state finding

High vacuum-pump control circuit does not prove excess vacuum

PTO Enable Switch Performance

Torque Management Request Output Signal

Turbocharger Boost Control Position Sensor B Circuit Intermittent/Erratic

Cruise Control Front Distance Range Sensor Left

Cruise Control Front Distance Range Sensor Right

Turbocharger Speed Sensor B Circuit

A turbo-speed plausibility mismatch with a bank-label caveat

Bank-two turbo-speed low requires an unchanging pulse signal

Separating a static high turbo-speed input from valid pulses

Turbocharger Speed Sensor B Circuit Intermittent

Turbo position remains low relative to its command

turbo vanes fail to return to their default open position

Turbocharger Boost Control Position Sensor B Performance - Stuck Low

Turbocharger Boost Control Position Sensor B Performance - Stuck High

Excessive Time To Enter Closed Loop Turbocharger A Boost Control

Excessive Time To Enter Closed Loop Turbocharger B Boost Control

A low boost-control limit uses a large sustained pressure error

High boost-control limit means actual boost exceeds the target

Turbocharger B Boost Control Position At Low Limit

Turbocharger B Boost Control Position At High Limit

A brake-module MIL request points to another controller’s evidence

Engine Hood Open

Fuel Mode Select Switch Circuit

Fuel Mode Select Switch Performance

Fuel Mode Select Switch Circuit Low

Fuel Mode Select Switch Circuit High

Fuel Mode Select Switch Circuit Intermittent/Erratic

Piston Cooling Oil Control Circuit/Open

Piston Cooling Oil Control Circuit Low

Piston Cooling Oil Control Circuit High

Piston Cooling Oil Control Circuit Performance/Stuck Off

Piston Cooling Oil Control Circuit Stuck On

Piston Cooling Oil Pressure Too Low

Coolant switching valve performance inferred from pressure changes

Fuel-level sensor A can be stuck even when its electrical value looks plausible

Fuel-level sensor B stuck monitoring uses consumption history

An A-or-B stuck result does not identify which fuel-level sender failed

Why wastegate A stuck-open depends on position normalization

Wastegate A stuck-closed is a timed control disagreement

Reading bank-two wastegate stuck-open without reversing the scale

How the controller classifies a bank-two wastegate closed-side jam

Auxiliary Ignition Switch On/Start Position Circuit

Auxiliary Ignition Switch On/Start Position Circuit Low

Auxiliary Ignition Switch On/Start Position Circuit High

Regeneration Control Switch Circuit/Open

Regeneration Control Switch Circuit Low

Regeneration Control Switch Circuit High

engine overspeed detected without commanded fuel delivery

Alternative Fuel Disable Control Circuit/Open

Alternative Fuel Disable Control Circuit High