“Engine power reduced” warning came on
This message means the computer has deliberately limited throttle because it can’t trust what the throttle system is telling it.
What this usually means
“Engine Power Reduced” (or “Reduced Power Mode”) isn’t the engine failing — it’s the computer choosing to cap power. Modern cars have no throttle cable; the pedal is a sensor, the throttle is a motor, and the computer sits between them. If the two pedal-position signals disagree, the throttle body’s feedback doesn’t match its commands, or wiring between them drops out, the computer can no longer verify that the throttle will do what your foot asks. Its safety response is to clamp throttle opening — sometimes to little more than idle. The most common real-world causes are a failing throttle body, a worn accelerator-pedal sensor, or corroded connectors and wiring between them, and the fault is frequently intermittent, which is why the warning can vanish after a restart and return a week later.
Most likely causes
- highFailing electronic throttle bodyWorn position-sensor tracks or a sticking throttle motor make the throttle’s reported position disagree with what was commanded — the textbook trigger for reduced power.
- mediumAccelerator pedal position sensor faultThe pedal contains redundant sensors that must agree. When one drifts, the computer stops trusting the pedal and limits power.
- mediumWiring or connector problemsCorroded, chafed, or loose connections in the throttle circuit cause intermittent signal dropouts — a common culprit when the warning comes and goes.
- mediumDirty throttle bodyHeavy carbon buildup can physically bind the throttle plate enough that it can’t reach commanded positions, which reads as a mismatch.
- lowGround or charging-system issuesUnstable voltage or a poor ground skews sensor readings across the throttle circuit and can trip the fault without any single part being bad.
How urgent is it?
Redline can’t determine from a symptom or code alone whether your car is safe to drive.
Typical fix & cost
The stored throttle-system codes localize the fault to the pedal side, the throttle-body side, or the wiring between. Throttle-body replacement (with a relearn procedure afterward) is the most common repair; a pedal sensor or connector repair covers most of the rest. Cleaning helps only when buildup is genuinely the cause — codes indicating signal disagreement usually mean a failing component, not dirt.
Typical range: $150–$1,200
Cleaning or a connector repair is the low end; a throttle body or pedal assembly with programming is the high end, varying widely by vehicle.
The price depends on which cause it turns out to be, so confirm the cause before paying. Diagnose this for my car →
Start a case with what you’re noticing. Redline weighs these causes against your car’s evidence and names the check that would settle it.
Common questions
The warning went away after I restarted the car — is it fixed?
No. A restart clears the mode, not the cause, and throttle faults are classically intermittent. The code is still stored, and the mode can return without warning — including at highway speed — so get it diagnosed even if the car currently drives fine.
Why does the car limit power instead of just turning on a warning light?
Because the fault is in the system that controls acceleration itself. If the computer can’t verify the throttle will respond correctly to your foot, capping power is its way of preventing unintended acceleration or a stuck throttle.
Can I just clean the throttle body myself?
If buildup is the cause, cleaning can genuinely fix it, and it’s a reasonable first step on a high-mileage car. But codes pointing to sensor disagreement usually mean worn electronics that cleaning won’t cure, and some cars need a throttle relearn after cleaning to idle properly.
Related OBD-II codes
If your car has stored a trouble code, these often come with this symptom:
Related symptoms
General guidance, not a substitute for a hands-on inspection. Cost ranges are broad reference ranges, not quotes. For safety-related issues, have the car inspected before driving.
Seeing this on your car?
Every problem becomes a Case. Tell Redline what the car is doing: it shows what the evidence supports, what’s still missing, and what to check next, before you approve a repair.
“Inner pad ~1 mm. Outer pad 3 mm.”
Next: check the slide pins move freely before buying parts.