What Does P0077 Mean?
This code indicates the ECM has detected a high voltage or short-to-power condition on the intake VVT oil control solenoid circuit for bank 1. The control signal voltage remains higher than expected, preventing proper PWM modulation of the solenoid. This causes the VVT system to operate at maximum advance or default timing, leading to rough idle, reduced performance, and possible engine knock.
Common Causes
35%
Short-to-battery-voltage in the VVT solenoid control wire contacting another powered circuit or fused source
30%
Failed VVT solenoid with open coil winding preventing current flow through the control circuit
20%
Poor ground connection at the solenoid or ECM causing voltage to remain high on the control circuit
15%
Faulty ECM with open or failed low-side driver transistor unable to pull the circuit low
Diagnostic Steps
1
Disconnect the VVT solenoid and measure coil resistance. A reading of OL (open/infinite) confirms an open coil. Normal specification is 6.5-8.5 ohms at 68°F (20°C).
2
With the solenoid disconnected, measure voltage on the control wire at the harness connector with key on engine off. Voltage near battery level (12-14V) with the solenoid disconnected suggests a short-to-power in the harness.
3
Verify ECM ground integrity by measuring resistance from ECM ground pins to battery negative. Should be less than 0.5 ohms. Clean and retighten all engine and ECM ground connections.
4
If wiring and solenoid are normal, use a scan tool to command the solenoid on and off while monitoring the control circuit voltage at the ECM connector. A stuck-high signal indicates an ECM driver failure.
5
After repair, clear codes and perform a VVT system relearn if required by the manufacturer. Verify intake cam advance responds to commanded duty cycle changes.
Estimated Repair Cost
$75 - $400
Parts + labor, varies by vehicle and location
This code indicates the ECM has detected a high voltage or short-to-power condition on the intake VVT oil control solenoid circuit for bank 1. The control signal voltage remains higher than expected, preventing proper PWM modulation of the solenoid. This causes the VVT system to operate at maximum a...
The most common cause of P0077 (Intake Valve Control Solenoid Circuit High (Bank 1)) is: Short-to-battery-voltage in the VVT solenoid control wire contacting another powered circuit or fused source
Typical repair costs for P0077 range from $75 to $400, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Incorrect VVT operation can cause engine knock under load and reduced power output. If the timing is excessively advanced, detonation may occur during acceleration, potentially causing engine damage.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0077 to identify the root cause.
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Quick Info
Category
Powertrain
System
Variable Valve Timing (VVT) System
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
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