What Does P1558 Mean?
The ECM has detected an electrical fault in the electronic throttle control system. This could indicate a problem with the throttle actuator motor, position sensors, or associated wiring preventing proper throttle control.
Safety Warning
Vehicle may enter limp mode with reduced power or fail to accelerate properly. Loss of throttle control is a serious safety concern; avoid highway driving until repaired.
Common Causes
35%
Failed throttle body motor or worn brushes in throttle actuator
25%
Throttle position sensor failure or internal short circuit
20%
Damaged wiring or poor connection at throttle body connector
12%
Carbon buildup causing mechanical binding of throttle plate
8%
ECM internal throttle control circuit failure
Diagnostic Steps
1
Step 1: Inspect throttle body connector for corrosion, bent pins, or moisture; ensure secure connection
2
Step 2: Check throttle position sensor voltages at idle (typically 0.5-0.9V APP1, different range APP2); verify smooth transition to WOT
3
Step 3: Measure throttle actuator motor resistance across motor terminals (typically 2-10 ohms depending on design)
4
Step 4: Inspect throttle plate for carbon buildup and binding; clean if necessary with approved throttle body cleaner
5
Step 5: Check for proper battery voltage supply and ground circuits at throttle body with key on
Estimated Repair Cost
$200 - $900
Parts + labor, varies by vehicle and location
The ECM has detected an electrical fault in the electronic throttle control system. This could indicate a problem with the throttle actuator motor, position sensors, or associated wiring preventing proper throttle control.
The most common cause of P1558 (Throttle Actuator Electrical Malfunction) is: Failed throttle body motor or worn brushes in throttle actuator
Typical repair costs for P1558 range from $200 to $900, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle may enter limp mode with reduced power or fail to accelerate properly. Loss of throttle control is a serious safety concern; avoid highway driving until repaired.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1558 to identify the root cause.
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Quick Info
Category
Powertrain
System
Electronic Throttle Control
Difficulty
Type
Manufacturer
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