Engine-CodesBuick – P1843 Buick

P1843 Buick Code - 1-2 Shift Solenoid Circuit High Input Voltage

Quick Answer

The P1843 Buick code indicates a problem with the 1-2 shift solenoid circuit having high input voltage. Common causes include Faulty 1-2 shift solenoid, Wiring issues in the shift solenoid circuit, Malfunctioning PCM. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means
P1843 Buick indicates 1-2 Shift Solenoid Circuit High Input Voltage.
Common causes
Common causes include Faulty 1-2 shift solenoid, Wiring issues in the shift solenoid circuit, Malfunctioning PCM.
Severity
High - diagnose this code as soon as possible.
Can I drive?
Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
Table of contents Created and updated by William Orellana on Sep 17, 2024
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Code P1843 Buick Description

The P1843 Buick code indicates a problem with the 1-2 shift solenoid circuit having high input voltage. In an automatic transmission, shift solenoids are responsible for controlling the flow of transmission fluid to engage the gears. The 1-2 shift solenoid specifically controls the shift from first gear to second gear. When the PCM (powertrain control module) detects that the voltage in the 1-2 shift solenoid circuit is too high, it triggers this diagnostic trouble code.

OBDII Code P1843 Buick - 1-2 Shift Solenoid Circuit High Input Voltage
P1843 Buick Code - 1-2 Shift Solenoid Circuit High Input Voltage

Common Causes of P1843 Buick

  1. Faulty 1-2 shift solenoid
  2. Wiring issues in the shift solenoid circuit
  3. Malfunctioning PCM
  4. Transmission fluid pressure problems
  5. Electrical issues in the transmission system

Symptoms of P1843 Buick

  1. Harsh shifting between first and second gears
  2. Delayed or erratic shifting
  3. Failure to shift from first to second gear
  4. Decreased fuel efficiency
  5. Poor acceleration

How to Fix P1843 Buick

  1. Begin by conducting a thorough inspection of the shift solenoid circuit and wiring to identify any visible damage or loose connections.
  2. Test the 1-2 shift solenoid using a multimeter to check for proper resistance and continuity.
  3. Inspect the transmission fluid level and condition to ensure it is at the correct level and not contaminated.
  4. If the shift solenoid is found to be faulty, replace it with a new one and clear the trouble code from the PCM.
  5. Test drive the vehicle to ensure that the shifting is smooth and the code does not reappear.

Cost to Fix P1843 Buick

The cost of repairing a P1843 Buick code can vary depending on the specific cause of the issue and the labor rates in your area. On average, you can expect to pay between $200 and $500 for parts and labor to address this problem. Keep in mind that diagnostic time and labor rates at auto repair shops can vary, so it's recommended to get a few quotes from different shops to find the best price.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

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