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 that controls the car's transmission is having trouble checking its own operations. It's like a watchdog that is supposed to keep an eye on things but can't do its job properly.
The Transmission Control Module (TCM) has a built-in system to monitor its own operations, known as a watchdog. This error indicates a problem with the watchdog's ability to verify the TCM's internal processes.
The P171E code is triggered when the Transmission Control Module detects a fault in its internal watchdog mechanism. This mechanism is designed to ensure the TCM's operations are within expected parameters. A plausibility error suggests that the TCM's self-checks are failing or producing inconsistent results.
• Check Engine Light illuminated
• Transmission may not shift properly
• Vehicle may go into limp mode
• Faulty Transmission Control Module
• Software issues within the TCM
• Electrical problems such as poor connections or damaged wiring
Transmission Control Module (TCM): A computer that controls the transmission's functions.
Watchdog: A system that monitors the proper operation of a device.
• Scan the vehicle for OBD-II codes and note any additional codes.
• Inspect the TCM and its wiring for damage or loose connections.
• Check for any software updates for the TCM.
• Repair or replace damaged wiring or connections to the TCM.
• Reprogram or update the TCM software.
• Replace the Transmission Control Module if necessary.
• OBD-II scanner
• Multimeter
• Basic hand tools
$300 - $1,200
Moderate
• Chevrolet Malibu
• Ford Focus
• Toyota Camry
• Regularly update vehicle software.
• Ensure electrical connections are secure.
• Conduct periodic inspections of the TCM.
Transmission Control Module Issue
• Avoid driving the vehicle until the issue is diagnosed.
• Consult a professional mechanic for a thorough inspection.
Check if the vehicle's powertrain warranty covers TCM issues.
This code has been associated with newer vehicles featuring advanced transmission control systems.
Moderate – It is advisable to address this issue soon to avoid potential transmission damage.
Ignoring transmission issues can lead to unsafe driving conditions. Always ensure your vehicle is in good working order.
• Vehicle must be in a safe, stationary position.
• Engine should be off before inspecting electrical components.
The Transmission Control Module is typically located near the transmission or in the engine bay.
Q: Can I drive with a P171E code?
A: It's not recommended to drive with this code as it could lead to transmission problems.
Q: How do I reset the TCM?
A: Resetting the TCM usually requires a professional scan tool. Consult a mechanic for assistance.
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