P2078 code meaning
Intake Manifold Tuning (IMT) Valve Position Sensor/Switch Circuit High (Bank 1)
Powertrain system Generic code P20xx codes Check engine light
What P2078 means
Opposite of P2077: the bank 1 valve feedback sits above its upper plausible limit. Typical triggers are a short to battery or 5 V on the signal line, or an open sensor ground. Because GM's percentage scale is reversed, its tables treat a position of 5 % or less as high (2007, 2015, 2018; the 2006 table names 0.05 %), with 320 failures in 400 samples and Type B. GM's newer 2023/2024 logic instead watches for a raw voltage above roughly 4.8 V. On FCA's 3.5L V6 (2007-2010) P2078 is the second manifold tuning valve code next to P2077, and the Chrysler tip warns against replacing the whole manifold before testing the actuator output. Ford lists the code without MIL. Note that GM blocks its stuck-valve checks while this code is active.
P2078 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyEasy, DIY possible
- Typical labor0.3 to 2 hours
- Clears after repairAfter a drive cycle
Symptoms of P2078
- Check engine light (GM Type B; Ford without MIL)
- Valve monitoring suspended
- Possibly less power in one rpm band
Common causes of P2078
- Most likelySensor ground open, e.g. pushed-back pin in the connector
- PossibleSignal wire shorted to 5 V reference or battery voltage
- PossibleElectronics of the actuator unit defective
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Imt position sensor
What each part of P2078 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 0 | Area: fuel and air metering and auxiliary emission controls. |
| 78 | The exact fault in that area. |
What to do next
- Note P2078 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P2078
What does P2078 mean?
P2078 means "Intake Manifold Tuning (IMT) Valve Position Sensor/Switch Circuit High (Bank 1)". Opposite of P2077: the bank 1 valve feedback sits above its upper plausible limit. It is a generic code, so it means the same on every make.
Is it safe to drive with P2078?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P2078 fail an emissions test?
Yes, it can. P2078 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P2078 to fix?
Difficulty: easy. A typical repair takes 0.3 to 2 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P2078 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.