P0957
UniversalThe Powertrain Control Module (PCM) has detected a low voltage condition in the Automatic Shift Manual (ASM) mode circuit. This circuit is responsible for controlling the manual shift function of the transmission.
Medium SeverityThe vehicle's computer has detected an abnormally low voltage reading in the circuit that controls the Automatic Shift Manual (ASM) transmission mode. This can lead to problems with the transmission's ability to shift gears, particularly when attempting to use manual shifting features, and may result in erratic or harsh shifting.
⚠️ Before You Begin (Safety First)
Always ensure your vehicle is on a level surface and securely supported with jack stands if you need to go underneath. Disconnect the battery before working on any electrical components to prevent accidental shorts or injury. Allow engine and transmission components to cool before handling.
Common Symptoms
- Check Engine Light illuminated
- Inability to use manual shift mode (e.g., paddle shifters, tiptronic)
- Harsh or erratic transmission shifts
- Delayed gear engagement
- Transmission stuck in "limp mode" (often 3rd gear)
- Vehicle may not shift out of park
Common Causes
- Faulty wiring or corroded connectors in the ASM mode circuit
- Short circuit to ground within the ASM mode circuit
- Defective ASM mode switch (if applicable)
- Internal transmission fault or solenoid issue
- Faulty Transmission Control Module (TCM) or Powertrain Control Module (PCM)
Frequently reported on: All Makes
Diagnostic Steps
- Inspect all visible wiring and connectors leading to the transmission and ASM mode switch for damage, corrosion, or loose connections.
- Use a multimeter to test for continuity and proper voltage in the ASM mode circuit, checking for shorts to ground.
- If equipped, test the functionality of the ASM mode switch using a multimeter to ensure it's operating correctly.
- Clear the P0957 code with an OBD-II scanner after repairs and test drive the vehicle to confirm the fix.
👨🔧 When to Call a Professional
If the vehicle exhibits severe transmission issues such as being stuck in a single gear, refusal to shift, or significant loss of power, have the vehicle professionally diagnosed and repaired immediately to prevent further transmission damage.
Commonly Asked Questions
What does ASM mode mean for my transmission?
ASM (Automatic Shift Manual) mode refers to the capability of an automatic transmission to be manually shifted by the driver, often using paddle shifters or a gear lever.
Can I ignore a P0957 code?
It is not recommended to ignore P0957, as it indicates a problem with transmission control that could lead to further damage or unsafe driving conditions.
Is it safe to drive with P0957?
Driving with P0957 may be safe for very short distances if the vehicle can still shift, but prolonged driving could lead to unpredictable shifting, increased wear, or transmission failure.
What's the most common fix for P0957?
Often, the most common fix involves repairing damaged wiring or replacing a faulty ASM mode switch, though more complex issues like TCM failure can also occur.
How expensive is it to fix P0957?
Repair costs vary widely; a simple wiring fix might be inexpensive, while a new transmission control module or internal transmission repair could be very costly, ranging from tens to hundreds or even thousands of dollars.