What is what does it mean when your car says engine power reduced?

When your car displays a message like "Engine Power Reduced," it indicates that the vehicle's computer (ECU) has detected a problem that could potentially damage the engine or other critical components. To protect the system, the ECU limits the engine's power output. Here's what it generally means:

• Reduced Performance: You'll likely notice significantly less acceleration and overall power. The car may struggle to climb hills or merge onto highways. This is the most immediate symptom.

• A Protective Measure: This reduction isn't just a malfunction; it's a safety mechanism. The car is preventing further damage that could occur if it were allowed to operate at full power with the detected issue.

• Underlying Problems: Several factors can trigger this warning. Common causes include problems with the:

  • Throttle Body: A dirty or malfunctioning throttle body can restrict airflow to the engine, leading to reduced power.
  • Fuel System: Issues with the fuel pump, fuel injectors, or fuel filter can result in insufficient fuel delivery.
  • Ignition System: Faulty spark plugs, ignition coils, or other ignition components can cause misfires and power loss.
  • Sensors: Malfunctioning sensors (like the mass airflow sensor or oxygen sensor) can provide incorrect data to the ECU, leading to incorrect adjustments and power reduction.
  • Turbocharger (if equipped): Problems with the turbocharger or its control system can cause a loss of boost pressure and reduced engine power.
  • Exhaust System: A clogged catalytic converter can restrict exhaust flow and reduce engine power.

• Check Engine Light: The "Engine Power Reduced" message is almost always accompanied by the Check Engine Light. This is because it is related to engine issue.

• What to Do:

  1. Safe Stop: If possible, safely pull over to the side of the road.
  2. Check for Obvious Issues: Look for anything obviously wrong, such as loose wires or fluid leaks. However, you likely won't be able to diagnose the problem yourself.
  3. Don't Ignore: Do not continue driving for long periods with the engine power reduced.
  4. Professional Diagnosis: Have your car diagnosed by a qualified mechanic as soon as possible. They can use diagnostic tools to read the error codes stored in the ECU and pinpoint the cause of the problem.

• Error Codes: The ECU stores Diagnostic Trouble Codes (DTCs) that provide clues about the nature of the problem. A mechanic can read these codes using a scan tool.