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

Our certified mechanics come to you · 12-month, 12,000-mile warranty

SCHEDULE P0078 DIAGNOSTIC 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 for $70.00. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $30.00 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$70.00$30.00
Toyota$70.00$30.00
BMW$70.00$30.00
SCHEDULE P0078 DIAGNOSTIC Get a fair and transparent estimate upfront

Check Engine Light

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
trouble codes
P0078

Fast and easy Check Engine Light is on Inspection service at your home or office.

SCHEDULE P0078 DIAGNOSTIC
Get a fair and transparent estimate upfront

Recent Check Engine Light is on Inspection reviews

Excellent Rating


YourMechanic Check Engine Light is on Inspection Service

Average Rating

4.5/5

Number of Reviews

3,484

Rating Summary
3,176
153
40
23
92
3,176
153
40
23
92

Richard

10 years of experience
415 reviews
Richard
10 years of experience
This is the second time I’ve had Richard work on my car. He always does an outstanding job and is quick, knowledgeable and professional. Highly recommended!!
2012 DODGE CHALLENGER - CHECK ENGINE LIGHT IS ON - LAS VEGAS, NEVADA

Michael

13 years of experience
372 reviews
Michael
13 years of experience
Mike was an absolute professional when he arrived. He walked me thru the whole process of my repairs and also made good recommendations for preventive issues. His mechanical knowledge and good customer services was a breath of air and greatly appreciated :-)
2007 CHEVROLET AVALANCHE - CHECK ENGINE LIGHT IS ON INSPECTION - MARIETTA, GEORGIA

Rodrigo

10 years of experience
85 reviews
Rodrigo
10 years of experience
Rodrigo was exactly on time, very professional and friendly. He assessed my car, let me know the exact problem when a previous mechanic from a shop in my area was unable to. I felt he was very honest and sincere letting me know the level of urgency that I deal with the issue. Absolutely no pressure. I will absolutely use Rodrigo the next time I need anything to do with my car and will tell everyone about him. This is such a great service, I will never go to another mechanic again. It is so convenient. I couldn’t be happier. :)
2013 SMART FORTWO - CHECK ENGINE LIGHT IS ON - LAS VEGAS, NEVADA

Ricardo

8 years of experience
223 reviews
Ricardo
8 years of experience
Great service and was very helpful on what maintenance my vehicle needed and what to expect in the future. Would definitely recommend to anyone and will.
2004 MITSUBISHI LANCER - CHECK ENGINE LIGHT IS ON - LOS ANGELES, CALIFORNIA

More related articles

Symptoms of a Bad or Failing Flexible Clutch Hose
Common signs include difficulty shifting, low clutch fluid, and feeling no resistance at the clutch pedal.
How to Find the Keyless Code on a Ford Explorer or Mercury Mountaineer
Many Ford Explorers and Mercury Mountaineers were manufactured with an option known as the Ford keyless entry keypad. Some models refer to it as SecuriCode as well. It...
P0222 OBD-II Trouble Code: Throttle/Pedal Position Switch/Sensor B Circuit Low Input
P0222 code definition Throttle/Pedal Position Switch/Sensor B Circuit Low Input What the P0222...

Related questions

Q: I replace the thermostat and was told to drive it for engine light to go out but its still on after 5 days what can i do?

Anytime a vehicle repair is performed to remedy faults that arise from a check engine light (CEL) diagnostic, at the conclusion of the repair, a professional mechanic uses an appropriate scan tool to turn OFF the check engine light. The...

Q: Car stopped randomly and didn't drive afterwards

Hello, thanks for writing in. The computer will go into a failure mode and may not allow the electronic throttle to open if it detects a major computer or sensor fault. There can be many possible failures that will cause...

Q: My car is losing coolant from tailpipe

Hi there. According to what you've described, it does sound like your mechanic was correct; a blown head gasket. The radiator reservoir leak may have lead to the blown head gasket by causing a low coolant level, thus resulting in...

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.

1-800-701-6230 · hi@yourmechanic.com