P0077 code definition
Intake Valve Control Solenoid Circuit High (Bank 1)
What the P0077 code means
P0077 is a generic OBD2 code that is shown when there is a problem with the Bank 1 intake valve control circuit. This code is triggered when the Engine Control Module (ECM) has tried to control the intake valve solenoid and found high readings in the circuit. The ECM will display a Check Engine Light until the sensor reads normal range of values. This code may be seen with P0076.
What causes the P0077 code?
Faulty intake valve control solenoid, Bank 1
Intake valve control solenoid circuit, Bank 1 has an open or short in its wiring
Intake valve control solenoid circuit, Bank 1 circuit has poor connection or a disconnected connector
What are the symptoms of the P0077 code?
The ECM triggers the Check Engine Light to be displayed on the dashboard after the out of range sensor reading is found
Acceleration may suffer
A decline in fuel economy might be noticed
How does a mechanic diagnose the P0077 code?
Connects a scan tool to the OBD2 port in the vehicle
Observes the freeze frame codes and the condition of the vehicle when the code was set
Performs a road test of the vehicle under the same conditions of the freeze frame data
Performs a visual inspection of the wiring and connectors for any damage or breaks
Checks for continuity in the wiring with a multimeter
Inspects the data stream for the intake control system with a scan tool
Checks for any out of range readings from the sensor
Common mistakes when diagnosing the P0077 code
Like any code, P0077 can be easy to diagnose as long as all steps are followed and none are skipped. The most common mistake is when the intake valve control solenoid is replaced without actually testing it; doing this may or may not fix the issue and all of the diagnostic steps will have to be performed again if they are skipped.
How serious is the P0077 code?
In most scenarios, the Check Engine Light being illuminated is the worst of the symptoms. When acceleration suffers and poor economy is noticed, the car must be repaired as soon as possible for safe driving and normal vehicle operation.
What repairs can fix the P0077 code?
- Repairing open or short in the intake valve control solenoid circuit
- Replacing or repairing connectors and wiring
- Replacing the solenoid control valve
Additional comments for consideration regarding the P0077 code
P0077 is typically a easy to diagnose code, but like any other sensor code the fault may be intermittent and difficult to locate. Proper diagnosis is critical to avoid replacing parts that operate properly.
The intake valve control solenoid is integral to modern engines that use variable valve timing. This optimizes fuel economy and helps with better acceleration. With P0077 present, the variable valve timing system cannot operate properly.
A scan tool is required for this code that will allow advanced sensor data to be read. This is used to confirm that the intake valve control solenoid is operating properly. Without the proper scan tool, it is much harder to diagnose this code.
Need help with a P0077 code?
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This article originally appeared on YourMechanic.com as P0077 OBD-II Trouble Code: Intake Valve Control Solenoid Circuit High (Bank 1) and was authored by Spencer Clayton.