What it means
IMT position sensor at bank 1 reads above upper plausibility — open signal or short to B+. The intake manifold runner control (IMRC) flaps tune intake geometry for filling efficiency across the rpm range; stuck flaps cost part-load torque and can set lean codes.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The Bank 1 intake manifold tuning valve changes the intake path, and its position sensor reports the valve position to the engine computer. P2078 sets when the sensor signal rises above the acceptable high limit, which can result from an open signal wire or a short to battery voltage.
Common causes
Most likely first.
- Open signal line
- Connector pins corroded - high contact resistance
- Supply wire pinched against B+ source
Symptoms
- Check-engine light
- Possible reduced engine power or acceleration
- Possible hesitation or rough running
How to diagnose it
- Review freeze-frame and live data for the Bank 1 IMT position signal to confirm it is stuck or driven high.
- Inspect the Bank 1 sensor connector and harness for an open signal wire, pulled terminals, corrosion, or insulation damage near a power source.
- Use the wiring diagram to identify the Bank 1 signal circuit and check it for an open or a short to battery voltage.
- Verify the sensor supply and ground, then observe whether the signal changes when the valve is commanded to move.
- Compare Bank 1 circuit readings and sensor response with the manufacturer's specification before replacing the sensor.
Common fixes
- Repair an open Bank 1 IMT signal wire or a signal wire shorted to battery voltage.
- Reconnect or replace damaged terminals at the Bank 1 sensor connector.
- Reroute or secure wiring that has been pinched against a power source.
- Replace the Bank 1 position sensor if the circuit is sound but its output remains too high.
Can I keep driving?
If the engine runs steadily, gentle driving may be possible, but avoid hard acceleration if response is reduced or erratic. A high signal can prevent the computer from correctly controlling the Bank 1 tuning valve and may worsen performance and emissions.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.