What Does P2078 Mean?
The PCM is detecting an abnormally high voltage signal from the intake manifold tuning valve position sensor circuit on Bank 1. This suggests an open circuit, short to voltage, or sensor failure.
Common Causes
35%
Open circuit in IMT sensor signal or ground wire
30%
Failed IMT position sensor with internal open circuit
15%
Disconnected or loose sensor connector
12%
Short to voltage in sensor signal wire
8%
Poor ground connection at sensor or PCM
Diagnostic Steps
1
Step 1: Check for proper connector engagement at IMT position sensor
2
Step 2: Measure voltage at sensor signal wire (should be ~0.5-4.5V, not constant 5V)
3
Step 3: Check continuity of signal wire from sensor to PCM with sensor disconnected
4
Step 4: Verify sensor ground circuit continuity to PCM and check for resistance
5
Step 5: Test sensor by applying 5V reference and ground, then measure signal output through range of motion
Estimated Repair Cost
$150 - $600
Parts + labor, varies by vehicle and location
The PCM is detecting an abnormally high voltage signal from the intake manifold tuning valve position sensor circuit on Bank 1. This suggests an open circuit, short to voltage, or sensor failure.
The most common cause of P2078 (Intake Manifold Tuning (IMT) Valve Position Sensor/Switch Circuit High Bank 1) is: Open circuit in IMT sensor signal or ground wire
Typical repair costs for P2078 range from $150 to $600, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle remains safe to operate but will experience reduced performance. The intake system will operate in a fixed default mode affecting acceleration and fuel economy.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P2078 to identify the root cause.
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Quick Info
Category
Powertrain
System
Engine Air Induction / Variable Intake System
Difficulty
Type
Generic (SAE)
Recommended Tools
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