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Engine-Codes – Generic – P1842

P1842 Code - 1-2 Shift Solenoid Circuit Low Input Voltage

Quick Answer

The P1842 diagnostic trouble code (DTC) indicates a problem with the 1-2 shift solenoid circuit in an automatic transmission. Common causes include Faulty 1-2 shift solenoid, Damaged wiring or connectors in the shift solenoid circuit, Blown fuse related to the transmission control module. 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
P1842 indicates 1-2 Shift Solenoid Circuit Low Input Voltage.
Common causes
Common causes include Faulty 1-2 shift solenoid, Damaged wiring or connectors in the shift solenoid circuit, Blown fuse related to the transmission control module.
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.
What is this?
Table of contents Created and updated by William Orellana on Sep 07, 2024
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Code P1842 Description

The P1842 diagnostic trouble code (DTC) indicates a problem with the 1-2 shift solenoid circuit in an automatic transmission. This code specifically points to a low input voltage in the circuit, which can prevent the proper operation of the shift solenoid. The shift solenoid is responsible for controlling the hydraulic pressure that engages the clutch packs to facilitate gear changes in the transmission.

OBDII Code P1842 - 1-2 Shift Solenoid Circuit Low Input Voltage
P1842 Code - 1-2 Shift Solenoid Circuit Low Input Voltage

Common Causes of P1842

  1. Faulty 1-2 shift solenoid.
  2. Damaged wiring or connectors in the shift solenoid circuit.
  3. Blown fuse related to the transmission control module.
  4. Malfunctioning transmission control module.
  5. Low transmission fluid levels or dirty fluid affecting solenoid operation.

Symptoms of P1842

  1. Erratic or delayed shifting between gears.
  2. Harsh or jerky gear shifts.
  3. Transmission slipping or struggling to engage gears.
  4. Illumination of the check engine light on the dashboard.
  5. Decreased fuel efficiency due to inefficient gear changes.

How to Fix P1842

  1. Begin by conducting a thorough diagnosis to pinpoint the exact cause of the low input voltage in the 1-2 shift solenoid circuit.
  2. Inspect and test the shift solenoid to determine if it is functioning correctly. Replace the solenoid if necessary.
  3. Check the wiring and connectors in the circuit for any damage or corrosion. Repair or replace as needed.
  4. Verify the integrity of the transmission control module and address any issues that may be causing the low input voltage.
  5. Clear the DTC and test drive the vehicle to ensure that the shifting issues have been resolved.

Cost to Fix P1842

The cost of repairing a 1-2 shift solenoid circuit with low input voltage can vary depending on the specific cause of the issue and the make and model of the vehicle. Typically, the replacement of a shift solenoid can range from $150 to $300, while addressing wiring or control module issues may increase the total repair cost. The labor rates at auto repair shops can range from $80 to $150 per hour, and additional diagnostic time may be required to accurately diagnose and repair the problem. It's advisable to consult with a professional mechanic to obtain a more accurate estimate based on your vehicle's specific needs.

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Code P1842 Information for Specific Makes

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.

Frequently Asked Questions about P1842 Code

1. What are the common symptoms of OBDII code P1842 (1-2 Shift Solenoid Circuit Low Input Voltage)?

The common symptoms of P1842 include harsh shifting between first and second gear, delayed or erratic shifting, and potential transmission slipping.

2. What are the possible causes of OBDII code P1842?

Potential causes of P1842 include a faulty 1-2 shift solenoid, damaged wiring or connectors in the solenoid circuit, low transmission fluid levels, or a malfunctioning transmission control module.

3. How can I diagnose the underlying issue causing OBDII code P1842?

Diagnosing P1842 involves checking the transmission fluid level and condition, inspecting the wiring and connectors related to the 1-2 shift solenoid, and using a professional OBDII scanner to pinpoint the exact fault.

4. Can I continue driving with OBDII code P1842 present?

It is not recommended to continue driving with P1842 active, as it can lead to further damage to the transmission and potentially result in unsafe driving conditions.

5. How can I repair OBDII code P1842 (1-2 Shift Solenoid Circuit Low Input Voltage)?

Repairing P1842 typically involves replacing the faulty 1-2 shift solenoid, repairing or replacing damaged wiring, ensuring proper transmission fluid levels, and clearing the trouble code with an OBDII scanner.

6. Is it possible for a DIY enthusiast to fix OBDII code P1842 at home?

Depending on your skill level and access to tools, it may be possible to address P1842 at home by following repair guides and videos. However, complex transmission issues may require professional expertise.

7. How much does it cost to repair OBDII code P1842?

The cost of repairing P1842 can vary depending on the extent of the issue and whether you choose to do the repairs yourself or seek professional help. Costs may include parts, labor, and diagnostic fees.

8. Can low transmission fluid cause OBDII code P1842 to trigger?

Yes, low transmission fluid levels can lead to P1842 being triggered, as inadequate fluid can affect the proper functioning of the 1-2 shift solenoid and other transmission components.

9. Are there any preventive measures to avoid OBDII code P1842 in the future?

Regularly servicing and maintaining your transmission, checking transmission fluid levels, addressing any leaks promptly, and avoiding aggressive driving can help prevent issues like P1842 from occurring.

10. How long does it typically take to repair OBDII code P1842?

The repair time for P1842 can vary depending on the specific cause of the issue, the availability of parts, and whether you are doing the repairs yourself or taking your vehicle to a professional.

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