Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This code means that the car's computer has detected a problem with the electrical circuit that controls shifting from second gear to first gear. It's like when a light switch is stuck on and won't turn off.
The P1871 code is triggered when the transmission control module (TCM) detects a high voltage condition in the 2-1 shift solenoid circuit.
The P1871 code indicates a fault in the transmission's 2-1 shift solenoid circuit, where the voltage is higher than expected. This can be due to a short circuit, faulty solenoid, or wiring issues. The solenoid is responsible for controlling the hydraulic pressure that enables the transmission to shift from second gear to first gear.
• Harsh or delayed shifting
• Transmission stuck in gear
• Check Engine Light illuminated
• Faulty 2-1 shift solenoid
• Short circuit in the wiring
• Faulty transmission control module (TCM)
Solenoid: An electromechanical device used to control fluid flow in the transmission.
TCM: Transmission Control Module, the computer that controls transmission operations.
• Use an OBD-II scanner to confirm the code.
• Inspect the wiring and connectors for damage.
• Test the 2-1 shift solenoid for proper operation.
• Replace the faulty 2-1 shift solenoid.
• Repair or replace damaged wiring or connectors.
• Replace the transmission control module if necessary.
• OBD-II scanner
• Multimeter
• Socket set
$200 - $500
Moderate
• Chevrolet Silverado
• GMC Sierra
• Cadillac Escalade
• Regular transmission fluid changes
• Inspect wiring harnesses periodically
• Avoid harsh driving conditions
Transmission Issue
• Avoid driving the vehicle until repaired.
• Consult a professional mechanic for diagnosis.
Transmission components may be covered under powertrain warranty.
This code has been commonly reported in vehicles with high mileage or those that have experienced transmission issues.
High – This issue can lead to transmission failure if not addressed promptly.
Driving with a malfunctioning transmission can be dangerous and may lead to further damage.
• Vehicle at operating temperature
• Transmission in drive mode
The 2-1 shift solenoid is located inside the transmission valve body.
Q: Can I drive with a P1871 code?
A: It's not recommended to drive with this code as it can cause further transmission damage.
Q: How do I reset the P1871 code?
A: After repairs, use an OBD-II scanner to clear the code from the vehicle's computer.
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