Reduced Engine Power: What It Means and What to Do

The Reduced Engine Power warning means the engine computer has limited throttle and power to protect the engine or for safety after detecting a fault, often in the electronic throttle system.

Get it checked soon
Can I keep driving? The car will usually move but with very limited acceleration, which can be dangerous when merging or crossing traffic. Drive slowly to a safe place or a shop, use hazard lights if you cannot keep up with traffic, and have it diagnosed promptly.
What it looks like
Typically a text message, sometimes with a car outline and a downward arrow or the check engine light.
Color
Usually an amber/yellow text message on the driver display, often with a car-and-arrow icon; most commonly seen on GM vehicles. Other makes show similar limp-mode messages.

Also called: engine power reduced, limp mode, reduced power warning, engine power is reduced message

Updated 2026-11-07 · By CarWhere Research

Why the reduced engine power comes on

Electronic throttle control uses two accelerator pedal sensors and two throttle position sensors that must agree with each other. If the computer sees a disagreement, a stuck throttle plate, a reference-voltage problem, or certain other faults such as overheating or transmission problems, it limits power to keep the vehicle controllable. The engine may idle normally but barely accelerate.

Common causes

  1. Dirty or failing electronic throttle body
  2. Throttle position sensor correlation fault
  3. Accelerator pedal position sensor fault
  4. Damaged wiring or corroded connectors at the throttle body or pedal
  5. Sensor reference-voltage short in a shared circuit
  6. Engine overheating or transmission faults triggering protection
  7. Low system voltage or a failing engine computer

What to do when the reduced engine power comes on

  1. Move to a safe lane or the shoulder and turn on hazards if you cannot maintain speed.
  2. Once stopped, turn the engine off for a minute and restart; this may temporarily restore power, but the fault remains.
  3. Check whether the check engine, temperature, or battery light is on.
  4. Have the codes read; throttle and pedal correlation codes are the most common.
  5. Inspect throttle body connectors and wiring for corrosion or damage.
  6. Avoid highway driving until it is fixed.

Symbols and colors vary by manufacturer; your owner’s manual has the exact meaning for your vehicle.

Related OBD-II codes

P2135 — Throttle/Pedal Position Sensor/Switch "A"/"B" Voltage Correlation

P2138 — Throttle/Pedal Position Sensor/Switch "D"/"E" Voltage Correlation

P2101 — Throttle Actuator "A" Control Motor Circuit Range/Performance

P2111 — Throttle Actuator "A" Control System - Stuck Open

P2112 — Throttle Actuator "A" Control System - Stuck Closed

P2119 — Throttle Actuator "A" Control Throttle Body Range/Performance

P0641 — Sensor Reference Voltage "A" Circuit/Open

P0651 — Sensor Reference Voltage "B" Circuit/Open

Reduced Engine Power FAQ

What does the reduced engine power mean?

The Reduced Engine Power warning means the engine computer has limited throttle and power to protect the engine or for safety after detecting a fault, often in the electronic throttle system.

Can I keep driving with the reduced engine power on?

The car will usually move but with very limited acceleration, which can be dangerous when merging or crossing traffic. Drive slowly to a safe place or a shop, use hazard lights if you cannot keep up with traffic, and have it diagnosed promptly.

Why does reduced engine power go away after restarting?

Restarting resets the protective strategy until the fault is detected again. The code stays stored, and the warning will return if the problem persists.

Can a dirty throttle body cause reduced engine power?

Yes. Carbon buildup can make the throttle plate stick or respond slowly, triggering a mismatch the computer treats as a safety fault. Cleaning or replacing the throttle body is a common fix.

Is reduced engine power the same as limp mode?

They are closely related. Both describe a protective mode that limits performance; the exact name and behavior vary by manufacturer.

Other dashboard warning lights

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Sources

General information written by CarWhere Research, not a diagnosis of your vehicle. When in doubt, stop in a safe place and follow your owner’s manual.