What it means
The auto-shift manual mode circuit reports a range/performance condition. Manual mode shift requests cannot be reliably interpreted.
At a glance
- Usually lights the check-engine light
How it works
The automatic transmission uses a manual-mode switch or position sensor to read requests such as upshift and downshift. The transmission control module compares the signal with its expected range as the selector is operated. P0956 sets when the signal is present but does not track those requests as expected.
Common causes
Most likely first.
- Switch contacts aged
- High-resistance contact
- Sensor element aged beyond calibration window
Symptoms
- Check engine or transmission warning light on
- Harsh, delayed, or missing shifts
- Possible limp mode (locked in one gear)
- Slipping or shuddering during gear changes
How to diagnose it
- Record freeze-frame data and check live data for manual-mode or upshift/downshift requests to see whether the reported position follows selector operation.
- Operate the selector through manual mode while watching the data and note whether the signal is out of range or changes inconsistently.
- Inspect the manual-mode switch or sensor, its connector, and wiring for wear, damage, loose pins, or corrosion.
- Check the switch or sensor output across its operating positions and compare it with the manufacturer's specification.
- If the input signal is correct at the sensor but incorrect at the transmission control module, test the wiring and connections between them.
Common fixes
- Clean and secure the manual-mode switch or sensor connector.
- Repair damaged wiring or poor electrical contacts in the manual-mode circuit.
- Replace a worn manual-mode switch or sensor that fails to track selector movement.
- Clear the code and confirm the input follows upshift and downshift requests during a road test.
Can I keep driving?
If shifts are normal and the transmission warning is not flashing, limit driving to necessary trips and avoid relying on manual mode. Stop if the transmission slips, shifts harshly, or becomes stuck in one gear, since continued driving can worsen transmission damage.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.