P0078 OBD-II Trouble Code: Exhaust Valve Control Solenoid Circuit (Bank 1)

Our certified mechanics come to you · Get a fair and transparent estimate upfront

Red-stars EXCELLENT RATING ON

Cost of diagnosing the P0078 code

P0078 is a diagnostic trouble code (DTC) for "Exhaust Valve Control Solenoid Circuit (Bank 1)". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $20.00 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.

Cars Estimate Credit towards follow-up repair Earliest Availability
Ford$20.00
Toyota$20.00
BMW$20.00
SCHEDULE P0078 DIAGNOSTIC Get a fair and transparent estimate upfront

P0078 code definition

Exhaust Valve Control Solenoid Circuit (Bank 1)

What the P0078 code means

P0078 is a generic OBD2 code indicating that the Engine Control Module (ECM) has tried to control the Bank 1 exhaust valve control solenoid, and found an issue present. This code may be seen in addition to P0079 and P0080.

What causes the P0078 code?

  • An open or short in wiring
  • Poor or faulty electrical connections
  • Failed control valve solenoid
  • Faulty ECM

What are the symptoms of the P0078 code?

  • Check Engine Light is on
  • Poor acceleration
  • Poor fuel economy

How does a mechanic diagnose the P0078 code?

  • Hooks up a professional grade scan tool to the vehicle's OBD2 port to detect any codes present

  • Observes the freeze frame data to note the conditions of the car when the Check Engine Light was first illuminated

  • Clears the codes and performs a road test under the circumstances seen in the freeze frame data

If the code reappears during the test drive:

  • Performs a visual inspection for all wiring and connectors associated with the valve control circuit

  • Uses a scan tool to observe the data from the exhaust valve control solenoid and its changes over time

If the sensor is operating properly, then the manufacturer's test of the ECM should be performed.

Common mistakes when diagnosing the P0078 code

Any Check Engine Light can be easy to diagnose, or difficult due to intermittent issues and other factors. Following all steps in the proper order and not condemning any part until it is inspected and tested is the route to success. The most common mistake is replacing the solenoid before proper diagnosis is performed.

How serious is the P0078 code?

The P0078 code typically just elicits the Check Engine Light without any other adverse engine issues noticed. In the circumstances where the vehicle accelerates poorly or the fuel mileage suffers, this code should be diagnosed by a qualified technician as soon as possible to ensure safe driving and normal operation.

What repairs can fix the P0078 code?

  • Repairing or replacing an open or short in wiring
  • Replacing faulty exhaust valve control solenoid
  • Replacing the ECM
  • Correcting any connection issues

Additional comments for consideration regarding the P0078 code

The exhaust valve control solenoid plays an important factor in modern engines that have variable valve timing and is needed for proper operation of this system. Variable valve timing adds better fuel economy and aides in acceleration in vehicles equipped with it. Most modern engines use variable valve timing of some type.

A professional level scan tool that allows you to see the advanced sensor data such as live readings, sensor voltage, and sensor resistance is required to accurately diagnose this code.

Need help with a P0078 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230 to have this issue resolved.

Check Engine Light
P0078
trouble codes

No more waiting rooms! Our mechanics will come to you to diagnose and fix the P0078 code.

SCHEDULE P0078 DIAGNOSTIC
Get a $20 credit for the follow-up repair

Recent Check Engine Light is on Inspection reviews

Excellent Rating

(6,328)

Rating Summary
5,857
225
52
35
159
5,857
225
52
35
159

Gustavo

17 years of experience
296 reviews
Gustavo
17 years of experience
Toyota Corolla - Check Engine Light is on - New Braunfels, Texas
As always, punctual and professional. He explains the problem thoroughly. I feel confident in his work and knowledge.

Greg

22 years of experience
86 reviews
Greg
22 years of experience
Mazda 3 - Check Engine Light is on - Queen Creek, Arizona
Greg was scheduled for 1:00 but he was able to come earlier and let us know right away. He was very thorough and spent his time going thru the entire car.

Gustavo

17 years of experience
296 reviews
Gustavo
17 years of experience
Lincoln Aviator - Check Engine Light is on - San Antonio, Texas
Made call before appt. -courteous-knowledgeable-got part need & did prompt repair after computer check.

Claud

8 years of experience
325 reviews
Claud
8 years of experience
Chevrolet Trax - Check Engine Light is on - Grosse Pointe, Michigan
Very good experience. He arrived on time. Explained what he was going to do. Completed the work and was thorough in what I needed for my next service in plain language vs car jargon. I'm a raving fan of Claud!


More related articles

P0069 OBD-II Trouble Code: Manifold Absolute Pressure/Barometric Pressure Correlation
P0069 P0069 Code Definition Manifold Absolute Pressure/Barometric Pressure Correlation What the P0069 code means What this code means is that the Powertrain Control Module is detecting contradictory readings from the manifold absolute pressure sensor and the barometric pressure sensor. ...
P0779 OBD-II Trouble Code: Pressure Control Solenoid B Intermittent
P0779 means that the Pressure Control Solenoid B, is receiving intermittent voltage signals due to low or dirty fluid, faulty solenoid, or module.
P0460 OBD-II Trouble Code: P0460 Fuel Level Sensor Circuit Malfunction
P0460 means there is a discrepancy between the fuel gauge and the actual fuel level in the tank. Which could be caused by a fuel sensor malfunction.

Related questions

Idling problems and flashing check engine light clicking noise being glove box by relay

The green key flashing is an immobilizer which can be caused for many reasons including a simple bad battery connection. The rough idle problem suggests a potentially bad idle air control module which regulates the air flow into the intake...

check engine light is on

Hi there. For the check engine light being on, to start, get a code reader and scan the codes to the computer to have a starting place with diagnosing your engine. The computer can store a lot of codes from...

My check engine light came on. Took it to Autozone and they came up with this code PO156. What is that

Hello, thank you for writing in. A P0156 troubleshooting code stands for an error with the oxygen sensor. There are multiple sensors, and this one is behind (further towards the rear) the catalytic converter. Several things may be happening. First,...

How can we help?

Our service team is available 7 days a week, Monday - Friday from 6 AM to 5 PM PST, Saturday - Sunday 7 AM - 4 PM PST.

1 (855) 347-2779 · hi@yourmechanic.com