Skip the auto shop - Our mechanics make house calls
  1. Home
  2. Articles
  3. P2078 OBD-II Trouble Code: Intake Manifold Tuning (IMT) Valve Position Sensor/Switch Circuit High

P2078 OBD-II Trouble Code: Intake Manifold Tuning (IMT) Valve Position Sensor/Switch Circuit High

Check Engine Light

P2078 code definition

Intake Manifold Tuning (IMT) Valve Position Sensor/Switch Circuit High

What the P2078 code means

This code will set if the Engine Control Module (ECM), or Powertrain Control Module (PCM), detects a problem with the position of the IMT valve.

What causes the P2078 code?

This code is set when the ECM sees a higher than expected voltage from the IMT position sensor. This can occur if the circuit has a short to power or a bad ground.

What are the symptoms of the P2078 code?

How does a mechanic diagnose the P2078 code?

The first step would be to connect a scan tool to the vehicle's OBD II connector, check for codes and observe the scan tool data for the IMT valve. Most vehicles have the capability to command the IMT valve motor to move. This should be done while watching the scan tool data and observing the valve itself. Often times it is necessary to do some disassembly to physically check the valve and sensor.

Common mistakes when diagnosing the P2078 code

Some IMT valves are vacuum actuated and others are electrically actuated. Vacuum lines to the vacuum actuated valves frequently plug, collapse or break. Failing to thoroughly inspect the vacuum lines can lead to misdiagnosis of the IMT valve.

Some disassembly is often necessary to see if the valve flap has broken away from its shaft. If this happens, all data and the valve motor will work, but drivability issues will still exist. A mechanic could dismiss this code as erroneous and suspect other components as the problem.

How serious is the P2078 code?

This code will likely cause drivability problems that the owner will find annoying. Outside of drivability issues this code will not cause damage to the motor or be unsafe for the passengers.

What repairs can fix the P2078 code?

  • Replacing the IMT valve (the sensor that this code indicates is the problem is most often part of the IMT valve assembly and will be replaced as a single unit)

  • Repairing wiring to the control circuit

  • Repairing vacuum lines that may be plugged or leaking

Additional comments for consideration regarding the P2078 code

This system is designed to enable better fuel mileage and performance in modern vehicles. The IMT valve directs the intake air flow from a long path at low RPM’s (Revolutions Per Minute) to a shorter path at higher RPM’s. This affects the MAF (Mass Air Flow) sensor’s data. The MAF, or as it is sometimes called, the MASS air flow sensor, is one of the primary sensors used by the ECM to calculate air/fuel ratio.

Need help with a P2078 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.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
Icon-warranty_badge-02

Skip the repair shop, our top-rated mechanics come to you.

At your home or office

Choose from 600+ repair, maintenance & diagnostic services. Our top-rated mechanics bring all parts & tools to your location.

Fair & transparent pricing

See labor & parts costs upfront, so you can book with confidence.

12-month, 12,000-mile warranty

Our services are backed by a 12-month, 12,000-mile warranty for your peace of mind.

Get A Quote

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE

More related articles

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...
How to Transfer a Car Title in Idaho
In order to prove ownership of a car, you must have the title. However, when a car is sold, given away or inherited, the title needs...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...


Related questions

Q: Stalling,bad fuel mileage,won't start without Acceleration, rough idling.

This may be related to a couple of different things. I would recommend checking the idle air control valve/module which works similar to the MAF sensor in that it regulates air intake as it is mixed with fuel prior to...

Q: Can I Look Up What Trouble Codes Mean?

When your Check Engine Light comes on or flashes on the dash for you it is indicating there is a problem in one of the vehicle systems and has set a trouble code stored in one of the modules’ memory....

Q: Opinion on certain oil additives

You should leave the manifold alone. A lot of times they crack so just leave that alone. Some of the additives do actually work to some extant. I know that molybdenum disulfide actually does work. It's a very good lubricant....