AutoCodes – Generic – P078A

P078A Code - Shift Timing Solenoid 'B'

Quick Answer

The Transmission Control Module (TCM) monitors the Shift Timing Solenoid 'B' circuit. Common causes include Faulty Shift Timing Solenoid 'B', Shift Timing Solenoid 'B' harness is open or shorted, Shift Timing Solenoid 'B' circuit poor electrical connection. 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: P078A indicates Shift Timing Solenoid 'B'.
Common causes: Common causes include Faulty Shift Timing Solenoid 'B', Shift Timing Solenoid 'B' harness is open or shorted, Shift Timing Solenoid 'B' circuit poor electrical connection.
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.

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Code Popularity 2,493

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on May 08, 2019

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P078A Description

The Transmission Control Module (TCM) monitors the Shift Timing Solenoid 'B' circuit. The TCM sets the OBDII code when the Shift Timing Solenoid 'B' is out of factory specifications.

OBDII Code P078A - Shift Timing Solenoid 'B' - AutoCodes.com — P078A Code - Shift Timing Solenoid 'B'

What does this mean?

What are the Possible Causes of the DTC P078A?

Faulty Shift Timing Solenoid 'B'
Shift Timing Solenoid 'B' harness is open or shorted
Shift Timing Solenoid 'B' circuit poor electrical connection

How to Fix the DTC P078A?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P078A code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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Need more information on how to fix the P078A code? Get Access to Factory Service Manuals

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Get the P078A code diagnosed by a professional: Find a repair shop in your area

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 P078A Code

1. What are the common symptoms of OBDII code P078A (Shift Timing Solenoid 'B')?

The common symptoms of code P078A include harsh shifting, delayed shifting, transmission slipping, and decreased fuel efficiency.

2. What can cause OBDII code P078A to appear?

Code P078A is typically caused by a faulty shift timing solenoid 'B', low transmission fluid, a malfunctioning transmission control module (TCM), or wiring issues.

3. How can I diagnose OBDII code P078A?

Diagnosing code P078A involves using an OBDII scanner to retrieve the code, checking the transmission fluid level and condition, inspecting the shift timing solenoid 'B', and testing the TCM and related wiring for faults.

4. How serious is OBDII code P078A?

Code P078A can lead to drivability issues and potential damage to the transmission if left unresolved. It is important to address the underlying cause promptly to prevent further damage.

5. Can I continue driving with OBDII code P078A?

It is not recommended to continue driving with code P078A present, as it can cause further damage to the transmission. It is best to address the issue as soon as possible.

6. How much does it typically cost to repair OBDII code P078A?

The cost of repairing code P078A can vary depending on the underlying cause. Replacing the shift timing solenoid 'B' can cost between $150 to $300, while addressing more complex issues like TCM replacement can cost upwards of $500.

7. Are there any DIY repair tips for OBDII code P078A?

While replacing the shift timing solenoid 'B' may be a straightforward DIY task for some, diagnosing and repairing other issues related to code P078A may require specialized tools and expertise. It is recommended to consult a professional mechanic for accurate diagnosis and repair.

8. Can a transmission flush help resolve OBDII code P078A?

A transmission flush may help resolve code P078A if the issue is related to low or degraded transmission fluid. However, if the root cause is a faulty shift timing solenoid 'B' or TCM, a flush may not fully address the problem.

9. How long does it take to repair OBDII code P078A?

The repair time for code P078A can vary depending on the exact cause and the extent of the repairs needed. Simple fixes like replacing the shift timing solenoid 'B' can be done within a few hours, while more complex issues may require a day or more.

10. Can OBDII code P078A be intermittent?

Yes, code P078A can sometimes appear intermittently, especially if the underlying issue is related to a loose connection or sporadic malfunction. It is important to address intermittent codes promptly to prevent potential transmission damage.