Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
Your car's computer that controls the transmission is having trouble understanding signals because something is interfering too much.
The Transmission Control Module (TCM) has detected an internal error due to excessive interference, which is affecting its ability to function correctly.
The P172C code indicates that the Transmission Control Module (TCM) has identified a Level 2 error due to interference exceeding the acceptable threshold. This interference disrupts the TCM's operations, potentially affecting the transmission's performance.
• Transmission slipping
• Erratic shifting
• Check engine light on
• Electrical interference from nearby components
• Faulty wiring or connectors
• Internal TCM malfunction
Transmission Control Module (TCM): A computer that controls the transmission's operation.
Interference: Unwanted electrical signals that disrupt normal operations.
• Use an OBD-II scanner to confirm the code.
• Inspect wiring and connectors for damage or corrosion.
• Check for any nearby sources of electrical interference.
• Repair or replace damaged wiring or connectors.
• Relocate components causing interference.
• Replace the Transmission Control Module if faulty.
• OBD-II scanner
• Multimeter
• Screwdriver set
$200 - $1000
Moderate
• Vehicle 1
• Vehicle 2
• Vehicle 3
• Regularly inspect and maintain wiring.
• Avoid placing electronic devices near the TCM.
• Ensure proper grounding of electrical components.
Transmission Control System Issue
• Avoid driving long distances until repaired.
• Consult a professional mechanic for diagnosis.
• Monitor for any changes in transmission behavior.
Check with your vehicle manufacturer for warranty coverage on transmission components.
This code has been associated with interference issues in modern vehicles with complex electronic systems.
Moderate – Addressing this issue soon can prevent further transmission damage.
Driving with transmission issues can be unsafe and may lead to further damage.
• Vehicle at operating temperature
• Transmission in normal driving mode
The Transmission Control Module is typically located near the transmission or under the vehicle's dashboard.
Q: Can I drive with a P172C code?
A: It's not recommended to drive long distances as it may cause further transmission issues.
Q: How can I reset the TCM?
A: Disconnecting the battery for a few minutes may reset the TCM, but it's best to address the underlying issue.
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