Engine

P0077 — Intake Valve Control Solenoid Circuit High (Bank 1)

Severity: medium Drive with care, to a shop

What P0077 means

P0077 sets when the engine computer detects higher than expected voltage in the control circuit of the Bank 1 intake valve timing (VVT) solenoid. Normally the PCM drives this solenoid to direct oil to the cam phaser, which shifts valve timing. A circuit fault prevents accurate control of that timing.

Symptoms

  • Check Engine light on
  • Rough or unstable idle
  • Reduced power and sluggish acceleration
  • Worse fuel economy
  • Possible hesitation at low rpm

Possible causes

  1. Failed intake VVT control solenoid
  2. Open, shorted or damaged wiring harness
  3. Control wire shorted to positive voltage
  4. Corroded or loose connector terminals
  5. Faulty driver circuit inside the PCM
  6. Dirty or sludged oil affecting the solenoid

How to diagnose

  1. Scan all codes and freeze frame data, clear the code and see if it returns
  2. Inspect the Bank 1 VVT solenoid connector and harness for chafing, corrosion and oil
  3. Check oil level and condition, and when it was last changed
  4. Measure solenoid coil resistance and compare to the service manual spec
  5. Test the wiring between solenoid and PCM for opens and shorts to power or ground
  6. Check supply voltage and control signal at the connector with the engine running
  7. Command the solenoid with a scan tool and watch the response
  8. If wiring and solenoid test good, evaluate the PCM

Common fixes

  • Replace the intake VVT control solenoid
  • Repair or replace damaged wiring and connectors
  • Clean and secure corroded terminals
  • Change oil and filter if contamination is the cause
  • Replace or reprogram the PCM (rare, after ruling out everything else)

Questions and answers

What does P0077 mean?

The PCM found too high a voltage in the Bank 1 intake VVT solenoid circuit. The solenoid itself or its wiring is the most common culprit.

Can I drive with P0077?

Briefly, if the engine runs smoothly. Power and fuel economy suffer though, so don't put off diagnosis.

How do I fix P0077?

Start by inspecting the connector and harness, then check solenoid resistance and oil condition. Most often the fix is a wiring repair or a new solenoid.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.