AutoCodes – Generic – P0078

P0078 Code - Exhaust Valve Control Solenoid Circuit Bank 1

Quick Answer

Exhaust valve timing control magnet retarder controls the shut/open timing of the exhaust valve by ON/OFF pulse duty signals sent from the Engine Control Module (ECM). Common causes include Faulty Exhaust Valve Timing Control Magnet Retarder, Exhaust Valve Timing Control Magnet Retarder harness is open or shorted, Exhaust Valve Timing Control Magnet Retarder circuit poor electrical circuit connector. 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: P0078 indicates Exhaust Valve Control Solenoid Circuit Bank 1.
Common causes: Common causes include Faulty Exhaust Valve Timing Control Magnet Retarder, Exhaust Valve Timing Control Magnet Retarder harness is open or shorted, Exhaust Valve Timing Control Magnet Retarder circuit poor electrical circuit connector.
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 20,951

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 Oct 25, 2019

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P0078 Description

Exhaust valve timing control magnet retarder controls the shut/open timing of the exhaust valve by ON/OFF pulse duty signals sent from the Engine Control Module (ECM). The longer pulse width retards valve angle. The shorter pulse width advances valve angle.

OBDII Code P0078 - Exhaust Valve Control Solenoid Circuit Bank 1 - AutoCodes.com — P0078 Code - Exhaust Valve Control Solenoid Circuit Bank 1

What does this mean?

What are the Possible Causes of the DTC P0078?

Faulty Exhaust Valve Timing Control Magnet Retarder
Exhaust Valve Timing Control Magnet Retarder harness is open or shorted
Exhaust Valve Timing Control Magnet Retarder circuit poor electrical circuit connector

How to Fix the DTC P0078?

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 P0078 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.

Need more information about the P0078 code?

Need more information on how to fix the P0078 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P0078 code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

P0078 Infiniti — Exhaust Valve Timing Control Magnet Retarder Circuit Bank 1
P0078 KIA — Exhaust Valve Control Solenoid Circuit Bank 1
P0078 Nissan — Exhaust Valve Timing Control Magnet Retarder Circuit Bank 1

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 P0078 Code

1. What are the common symptoms of OBDII code P0078?

The common symptoms of OBDII code P0078 include rough idling, engine stalling, decreased fuel efficiency, and illuminated Check Engine Light.

2. What does OBDII code P0078 indicate?

OBDII code P0078 indicates a malfunction in the Exhaust Valve Control Solenoid Circuit for Bank 1 in the vehicle's engine.

3. What are the possible causes of OBDII code P0078?

Possible causes of OBDII code P0078 include a faulty exhaust valve control solenoid, damaged wiring or connectors in the circuit, low engine oil level, or a malfunctioning PCM.

4. How can I diagnose the issue related to OBDII code P0078?

Diagnosing the issue related to OBDII code P0078 involves inspecting the exhaust valve control solenoid, checking the wiring and connectors for any damage, verifying the engine oil level, and performing a scan tool test.

5. How serious is OBDII code P0078?

OBDII code P0078 should be addressed promptly as it can lead to engine performance issues and potential damage if left unresolved for an extended period.

6. Can I continue driving with OBDII code P0078 illuminated?

It is not recommended to continue driving with OBDII code P0078 illuminated, as it can cause further damage to the engine and may result in decreased performance or even engine stalling.

7. How can OBDII code P0078 be repaired?

Repairing OBDII code P0078 typically involves replacing the faulty exhaust valve control solenoid, repairing or replacing damaged wiring or connectors, ensuring proper engine oil level, and resetting the fault code using a scan tool.

8. Can I repair OBDII code P0078 myself, or do I need a professional mechanic?

While some DIY enthusiasts may attempt to repair OBDII code P0078 themselves by following proper diagnostic procedures and using the right tools, it is recommended to consult a professional mechanic for accurate diagnosis and repair.

9. Are there any preventive maintenance tips to avoid OBDII code P0078?

To prevent OBDII code P0078, it is advisable to perform regular engine maintenance, including oil changes and inspections of the exhaust valve control solenoid and its related components.

10. How much does it cost to repair OBDII code P0078?

The cost to repair OBDII code P0078 can vary depending on the cause of the issue, the extent of the damage, and the labor rates of the repair shop. It is recommended to obtain quotes from different mechanics to compare prices.