Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This code means that the car's computer is having trouble controlling the part that helps the engine idle smoothly. It's like when you're trying to keep a ball balanced on your finger, but it keeps wobbling.
The P158D code indicates a problem with the idle speed control valve, which helps maintain the engine's idle speed. The control error suggests that the valve is not in the expected position.
The idle speed control valve is responsible for regulating the engine's idle speed by controlling the amount of air bypassing the throttle plate. A position control error means the valve is not responding as expected, possibly due to a mechanical or electrical fault.
• Erratic or unstable idle
• Engine stalling at idle
• Check Engine Light illuminated
• Faulty idle speed control valve
• Wiring issues or poor electrical connections
• ECU malfunction
ECU: Engine Control Unit, the computer that manages the engine's functions.
Throttle Body: A component of the air intake system that controls the amount of air entering the engine.
• Use an OBD-II scanner to confirm the code.
• Inspect the idle speed control valve for damage or blockage.
• Check the electrical connections and wiring to the valve.
• Clean or replace the idle speed control valve.
• Repair or replace any damaged wiring or connectors.
• Reprogram or replace the ECU if necessary.
• OBD-II scanner
• Multimeter
• Basic hand tools
$150 - $400
Moderate
• Toyota Camry
• Honda Accord
• Ford Focus
• Regular maintenance and cleaning of the throttle body and idle control valve.
• Ensure electrical connections are secure and corrosion-free.
• Use high-quality fuel to prevent deposits.
Engine Performance
• Do not ignore the Check Engine Light.
• Have the vehicle inspected by a professional if you experience stalling or idle issues.
Check with your vehicle manufacturer as some components may be covered under warranty.
This code has been reported in vehicles with higher mileage where components like the idle control valve are more likely to wear out.
Moderate – While the vehicle may still be drivable, ignoring this issue can lead to more severe engine performance problems.
Driving with a malfunctioning idle control system can lead to unexpected stalling, which may be dangerous.
• Engine at operating temperature
• Vehicle in idle state
The idle speed control valve is typically located on or near the throttle body of the engine.
Q: Can I drive with a P158D code?
A: It's possible to drive with this code, but it is not recommended as it can lead to engine stalling.
Q: How do I reset the Check Engine Light after fixing the issue?
A: You can use an OBD-II scanner to clear the code, or disconnect the battery for a few minutes to reset the ECU.
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Specialty · Fuel pressure tester
Helpful for no-start, lean, rich, injector, and fuel-delivery diagnosis.
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Specialty · Compression tester
Useful when misfire, mechanical condition, or low-cylinder-pressure problems are suspected.
Helpful when you need to rule out low compression or mechanical engine problems.
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