Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This code means the car doesn't know what gear it's in. It's like when you forget if you're holding a spoon or a fork.
The car's computer cannot determine the current gear position due to a malfunction.
The P18AF code is triggered when the transmission control module (TCM) fails to detect the gear position due to a malfunction in the gear position sensor or related components. This can affect the vehicle's ability to shift gears properly.
• Check Engine Light is on
• Transmission may not shift properly
• Vehicle may not start or move
• Faulty gear position sensor
• Wiring issues or poor connections
• Malfunctioning transmission control module
Transmission Control Module (TCM): A computer that controls the transmission functions.
Gear Position Sensor: A sensor that detects the current gear of the vehicle.
• Use an OBD-II scanner to confirm the code.
• Inspect the gear position sensor and related wiring for damage.
• Test the transmission control module for faults.
• Replace the gear position sensor if faulty.
• Repair or replace damaged wiring or connectors.
• Reprogram or replace the transmission control module if necessary.
• OBD-II scanner
• Multimeter
• Basic hand tools
$150 - $500
Moderate
• Chevrolet Cruze
• Buick Encore
• GMC Terrain
• Regularly inspect and maintain transmission components.
• Ensure wiring and connectors are secure and undamaged.
• Follow manufacturer service recommendations.
Sensor Issue
• Do not ignore the Check Engine Light.
• Have the vehicle inspected by a professional mechanic.
• Avoid driving the vehicle if it shows severe symptoms.
Check with your vehicle manufacturer as transmission components may be covered under warranty.
The P18AF code has been reported in various models with automatic transmissions, often related to sensor or wiring issues.
Moderate – Addressing this issue promptly can prevent further transmission damage.
Driving with a faulty transmission can be dangerous. Ensure repairs are carried out by a qualified technician.
• Vehicle must be in a safe, stationary position.
• Engine should be off before inspecting components.
The gear position sensor is typically located on the transmission housing or near the gear shifter.
Q: Can I drive with the P18AF code?
A: It's not recommended to drive with this code as it may lead to transmission issues.
Q: How do I reset the P18AF code?
A: After repairs, use an OBD-II scanner to clear the code. If the issue persists, further diagnosis is needed.
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