P0959 Fault Code

ASM Mode Circuit Intermittent

• What does that mean?
• Symptoms
• Causes
• Solutions

The P0959 fault code indicates an issue with the ASM (Automatic Shift Management) mode circuit. This can arise due to intermittent signals that affect the transmission's ability to shift gears properly. Such irregularities can lead to performance problems and affect the reliability of the vehicle's transmission system.

What are the symptoms of the P0959 code?

Symptoms associated with the P0959 code may include:

• Erratic or harsh shifting of gears while driving.
• The transmission may fail to shift into higher gears, leading to limited acceleration.
• Illumination of the check engine light on the dashboard.
• Unusual noises coming from the transmission during shifting.

What causes the P0959 code?

Common causes of the P0959 code include:

• Faulty wiring or connectors in the ASM mode circuit.
• Defective transmission control module (TCM) or engine control unit (ECU).
• Sensor malfunctions that provide inaccurate data to the TCM.
• Low transmission fluid levels or degraded fluid quality causing irregular operation.

How to fix P0959?

To resolve the P0959 fault code, consider the following steps:

• Inspect and repair any damaged wiring or connectors in the ASM circuit.
• Check and replace the transmission fluid if it is low or contaminated.
• Test the transmission control module for faults and reprogram or replace it if necessary.
• Clear the fault codes and take the vehicle for a test drive to ensure the issue has been resolved.