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 computer in charge of controlling the car's transmission has detected a problem with its own internal checks. It's like when a computer has a glitch and needs to be restarted.
The Transmission Control Module (TCM) has an internal watchdog mechanism that monitors its own operations. If the watchdog detects an electrical error, it triggers the P171D code.
The Transmission Control Module (TCM) is responsible for managing the operation of the transmission. It uses a watchdog timer to ensure that the system is functioning correctly. If the watchdog detects an anomaly in the electrical signals or operations, it flags a P171D error, indicating a potential fault within the TCM's internal circuits.
• Check Engine Light is on
• Transmission may not shift properly
• Vehicle may go into limp mode
• Faulty Transmission Control Module
• Electrical short or open circuit in the TCM
• Software glitch or corruption in the TCM
Transmission Control Module (TCM): A computer that controls the transmission's operation.
Watchdog Timer: A timer that monitors the operation of a system to ensure it is functioning correctly.
• Use an OBD-II scanner to confirm the P171D code.
• Inspect the TCM and its wiring for any visible damage.
• Check for any software updates for the TCM.
• Replace or repair the Transmission Control Module.
• Fix any wiring issues related to the TCM.
• Reprogram or update the TCM software.
• OBD-II Scanner
• Multimeter
• Screwdriver set
$300 - $1500
Difficult
• Chevrolet Malibu
• Ford Focus
• Toyota Camry
• Regularly update vehicle software.
• Perform routine checks on electrical connections.
• Avoid harsh driving conditions that may stress the transmission.
Transmission Control Issue
• Avoid driving at high speeds until the issue is resolved.
• Consult a professional mechanic for an accurate diagnosis.
• Consider towing the vehicle to a repair shop to prevent further damage.
Check if the vehicle's powertrain warranty covers TCM issues.
This code has been associated with vehicles that have experienced software glitches or electrical faults in the TCM.
High – This issue can lead to transmission failure if not addressed promptly.
Driving with a faulty transmission control module can be dangerous and may lead to further vehicle damage.
• Vehicle must be in a safe location.
• Ensure the vehicle battery is fully charged.
The Transmission Control Module is typically located near the engine or under the dashboard.
Q: Can I drive with a P171D code?
A: It's not recommended to drive with this code as it can lead to transmission issues.
Q: How do I reset the TCM?
A: A professional mechanic can reset the TCM using specialized equipment.
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