P1821
Shift Fork Position Sensor 1 System Voltage High Range Out
Severity
⚠️ MediumCan you drive?
Yes, but get it checked soon
Approx. repair cost
$33–167 (est.)
Symptoms
- Gear shifting problems
- Hard or abrupt shifts
- Transmission transition to emergency mode
- Check Engine Light Illuminates
- Reduced transmission efficiency
Causes
- Shift fork position sensor malfunction
- Short circuit in the sensor circuit
- Wiring harness damage
- Problems with the sensor power supply
- Transmission control module (TCM) malfunction
How to Fix
- Check the integrity of the sensor circuit
- Check resistance and sensor signal
- Scan all associated trouble codes
- If necessary, replace the fork position sensor
- Check and update TCM firmware if necessary