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Reduced Power Initial Checklist

An initial route for throttle, airflow, boost, EGR, and timing issues when the vehicle enters limp mode.

Guide step

Decide whether this is engine derate or transmission fail-safe first

A throttle-limited engine, weak boost, or airflow plausibility problem belongs in the reduced-power bucket. A vehicle stuck in one gear with harsh shifts belongs in the transmission limp-mode bucket even if the driver also says reduced power.

Guide step

Read all modules if possible

Reduced power can involve powertrain plus electronic throttle or transmission modules, so do not stop at one generic PCM code if the scan tool can reach more.

Guide step

Check sensor plausibility

MAF, throttle position, cam timing, and boost readings should agree with load and RPM. If they do not, the ECU may be limiting torque on purpose rather than reacting to a true mechanical power loss.

Guide step

Inspect connectors and basics

Connector fitment, low oil, carbon buildup, air leaks, and low system voltage can all mimic failed sensors or force protective derate behavior.

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Related codes

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P0101 — Mass Air Flow Circuit Range/Performance P0011 — A Camshaft Position Timing Over-Advanced or System Performance (Bank 1)P0016 — Crankshaft Position - Camshaft Position Correlation (Bank 1 Sensor A)P0401 — Exhaust Gas Recirculation Flow Insufficient Detected P00BD — Mass or Volume Air Flow A Circuit Range/Performance - Airflow Too High P0299 — Turbocharger/Supercharger Underboost Condition P2135 — Throttle/Pedal Position Sensor/Switch A/B Voltage Correlation P0121 — Throttle/Pedal Position Sensor/Switch A Circuit Range/Performance P0221 — Throttle/Pedal Position Sensor/Switch B Circuit Range/Performance P2101 — Throttle Actuator Control Motor Circuit Range/Performance P2119 — Throttle Actuator Control Throttle Body Range/Performance P2138 — Throttle/Pedal Position Sensor/Switch D/E Voltage Correlation P2176 — Throttle Actuator Control System - Idle Position Not Learned P0120 — Throttle/Pedal Position Sensor/Switch A Circuit P0122 — Throttle/Pedal Position Sensor/Switch A Circuit Low Input P0123 — Throttle/Pedal Position Sensor/Switch A Circuit High Input P0220 — Throttle/Pedal Position Sensor/Switch B Circuit P0222 — Throttle/Pedal Position Sensor/Switch B Circuit Low Input P0223 — Throttle/Pedal Position Sensor/Switch B Circuit High Input P2100 — Throttle Actuator Control Motor Circuit/Open P2106 — Throttle Actuator Control System - Forced Limited Power P2107 — Throttle Actuator Control Module Processor P2110 — Throttle Actuator Control System - Forced Limited RPM P2111 — Throttle Actuator Control System - Stuck Open P2112 — Throttle Actuator Control System - Stuck Closed P2102 — Throttle Actuator Control Motor Circuit Low P2103 — Throttle Actuator Control Motor Circuit High P2104 — Throttle Actuator Control System - Forced Idle P2105 — Throttle Actuator Control System - Forced Engine Shutdown P2118 — Throttle Actuator Control Motor Current Range/Performance P2120 — Throttle/Pedal Position Sensor/Switch D Circuit P2121 — Throttle/Pedal Position Sensor/Switch D Circuit Range/Performance P2130 — Throttle/Pedal Position Sensor/Switch F Circuit P2131 — Throttle/Pedal Position Sensor/Switch F Circuit Range/Performance P2132 — Throttle/Pedal Position Sensor/Switch F Circuit Low Input P2133 — Throttle/Pedal Position Sensor/Switch F Circuit High Input P2134 — Throttle/Pedal Position Sensor/Switch F Circuit Intermittent P2122 — Throttle/Pedal Position Sensor/Switch D Circuit Low Input P2123 — Throttle/Pedal Position Sensor/Switch D Circuit High Input P2127 — Throttle/Pedal Position Sensor/Switch E Circuit Low Input P2128 — Throttle/Pedal Position Sensor/Switch E Circuit High Input P0230 — Fuel Pump Primary Circuit P0231 — Fuel Pump Secondary Circuit Low P023F — Fuel Pump Secondary Circuit/Open P0627 — Fuel Pump A Control Circuit/Open P0628 — Fuel Pump A Control Circuit Low P0641 — Sensor Reference Voltage A Circuit/Open P0651 — Sensor Reference Voltage B Circuit/Open P0652 — Sensor Reference Voltage B Circuit Low P0653 — Sensor Reference Voltage B Circuit High P0697 — Sensor Reference Voltage C Circuit/Open P0698 — Sensor Reference Voltage C Circuit Low P0699 — Sensor Reference Voltage C Circuit High P0685 — ECM/PCM Power Relay Control Circuit/Open P0687 — ECM/PCM Power Relay Control Circuit High P0689 — ECM/PCM Power Relay Sense Circuit Low P0690 — ECM/PCM Power Relay Sense Circuit High P068A — ECM/PCM Power Relay De-Energized Performance Too Early P0233 — Fuel Pump Secondary Circuit Intermittent P025A — Fuel Pump Module Control Circuit/Open P025B — Fuel Pump Module Control Circuit Range/Performance P025C — Fuel Pump Module Control Circuit Low P025D — Fuel Pump Module Control Circuit High P06DA — Engine Oil Pressure Control Circuit/Open P06DB — Engine Oil Pressure Control Performance P06DD — Engine Oil Pressure Control Stuck Off P06DE — Engine Oil Pressure Control Stuck On P2227 — Barometric Pressure Circuit Range/Performance P2279 — Intake Air System Leak P2287 — Injector Control Pressure Sensor Circuit Intermittent P1516 — Throttle Actuator Control Module Throttle Actuator Position Performance P060A — Internal Control Module Monitoring Processor Performance P061B — Internal Control Module Torque Calculation Performance P2228 — Barometric Pressure Circuit Low P2229 — Barometric Pressure Circuit High P2261 — Turbo/Supercharger Bypass Valve Mechanical P2262 — Turbo/Supercharger Boost Pressure Not Detected Mechanical P0556 — Brake Booster Pressure Sensor Circuit Range/Performance P0557 — Brake Booster Pressure Sensor Circuit Low P2177 — System Too Lean Off Idle Bank 1 P2179 — System Too Lean Off Idle Bank 2 P0069 — Manifold Absolute Pressure - Barometric Pressure Correlation P0490 — Exhaust Gas Recirculation Control Circuit High P0558 — Brake Booster Pressure Sensor Circuit High P0559 — Brake Booster Pressure Sensor Circuit Intermittent

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Related symptoms

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Reduced Power Stuck in Limp Mode