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P0390 Fault-Error Code Camshaft Position Sensor B Circuit (Bank 2)

Updated: Oct 4

What is the P0390 Fault-Error Code?

The P0390 Fault-Error Code refers to "Camshaft Position Sensor 'B' Circuit Intermittent." This code indicates that the engine control module (ECM) or engine control unit (ECU) has detected a problem with the engine's Bank 2 camshaft position sensor 'B' circuit.



P0390

This error code typically means:

Camshaft Position Sensor 'B' Circuit (Bank 2): This indicates the specific camshaft position sensor experiencing a circuit problem.


NOTE: It is important to consult the vehicle model and manufacturer specifications to determine which specific part or circuit is "Bank 2" and "Circuit B." Different vehicles and manufacturers may use different sensors and circuits, so the term "Camshaft Position Sensor 'B' Circuit" may not refer to the same part on every vehicle.



What are the symptoms of P0390 Fault-Error Code?

Some common symptoms of the P0390 Fault-Error Code include:

Engine Malfunction Light On: The engine malfunction light or service light on the vehicle's dashboard comes on.


Engine Misfires or Rough Idle: A faulty camshaft position sensor 'B' can cause the engine to misfire or idle rough. You may notice the engine hesitating, stumbling or shaking.



Poor Fuel Efficiency: An incorrect camshaft position sensor 'B' can lead to incorrect fuel injection timing, resulting in poor fuel efficiency and increased fuel consumption over time.


Engine Stalls or Hesitates: The engine may stall, hesitate, or exhibit poor acceleration due to incorrect camshaft timing readings.



Hard Starting: If the camshaft position sensor 'B' fails completely or provides erratic readings, the engine may have difficulty starting or may not start at all.


Reduced Engine Performance: The engine may lack power, respond slowly to the throttle, or exhibit poor acceleration due to incorrect camshaft timing.


Transmission Shifting Issues: In some cases, a faulty camshaft position sensor 'B' can affect the transmission's shift patterns, leading to erratic or harsh shifts.



What could be the causes of the P0390 Fault-Error Code?

There are several possible causes that can trigger the P0390 fault/error code:

Faulty Camshaft Position Sensor 'B': The sensor itself may be faulty, damaged or defective, causing intermittent signal interruptions.


Wiring Issues: The wiring harness connected to the camshaft position sensor 'B' may have opens, shorts or damage causing intermittent loss of signal.



Connector Issues: The electrical connector to the camshaft position sensor 'B' may be loose, damaged, corroded or improperly connected, affecting signal integrity.


Sensor Installation Issues: Improper installation of the camshaft position sensor 'B' can result in poor connection or alignment issues, resulting in intermittent signal issues.


ECM/ECU Issues: In rare cases, a faulty engine control module (ECM) or engine control unit (ECU) can cause intermittent signal interruptions from camshaft position sensor 'B'.



Mechanical Engine Problems: Physical damage or wear to the camshaft or related components can affect the camshaft position sensor readings.


Interference: Radio frequency interference (RFI) from other electronic components or devices can disrupt the signal from camshaft position sensor 'B', causing intermittent signal issues.


Environmental Factors: Exposure to extreme temperatures, humidity or contaminants can damage the camshaft position sensor 'B' or its wiring, causing intermittent signal issues.



What Steps Should Be Followed to Resolve P0390 Fault-Error Code?

Here are the steps to follow to resolve the P0390 fault/error code:

Diagnostic Scan: Use an OBD-II scanner to retrieve trouble codes stored in the engine control module (ECM) or engine control unit (ECU). This will confirm trouble code P0390 and provide additional information on related codes or issues.


Visual Inspection: Visually inspect the camshaft position sensor 'B', wiring harnesses and electrical connectors for any obvious damage, corrosion or loose connections. Check the sensor mounting and ensure it is installed properly.



Sensor Test: Test camshaft position sensor 'B' using a multimeter to measure its resistance and voltage output. Follow manufacturer's specifications to ensure the sensor is functioning properly.


Wiring and Connector Inspection: Check the wiring harness connected to the camshaft position sensor 'B' for open, shorted or damaged. Check the electrical connectors for corrosion, damage or poor connections. Repair or replace any faulty wiring or connectors as necessary.



Engine Timing Inspection: Check timing belt or timing chain for wear, damage or misalignment. Verify that camshaft timing marks are properly aligned and timing components are in good condition.


ECM/ECU Inspection: Although rare, a faulty engine control module (ECM) or engine control unit (ECU) can cause code P0390. Perform a thorough inspection of the ECM/ECU and its connections to eliminate this possibility.



Clear Trouble Codes: After identifying and repairing the problem, clear the trouble codes using the OBD-II scanner and test drive the vehicle to make sure the problem is resolved.

What Are the Long-Term Effects of the P0390 Fault-Error Code?

Some possible long-term consequences of the P0390 fault/error code include:

Poor Engine Performance: A faulty camshaft position sensor 'B' can cause incorrect timing of the engine valves, resulting in reduced engine performance, power and response.



Poor Fuel Efficiency: Incorrect camshaft timing can cause improper fuel injection and combustion, leading to reduced fuel efficiency and increased fuel consumption over time.


Engine Misfires: The engine may experience frequent misfires, causing the engine to run rough, idle poorly, or even stall. This can cause further damage to the engine and its components.



Increased Emissions: A faulty camshaft position sensor 'B' can affect the engine's emissions control systems, causing increased emissions of harmful pollutants and potentially causing the vehicle to fail emissions tests.


Engine Damage: Continuing to operate with a faulty camshaft position sensor 'B' can cause serious engine damage, including damage to valves, pistons and other internal components. This can lead to costly repairs or even engine failure.



Transmission Issues: Incorrect camshaft position readings can affect the transmission's shift modes, leading to erratic or harsh shifts, reduced transmission life and possible transmission failure.


Safety Concerns: Engine performance degradation, stalling or engine failure due to faulty camshaft position sensor 'B' can pose safety risks, especially when driving at high speeds or in heavy traffic.



Increased Repair Costs: Ignoring the P0390 trouble code can lead to additional damage to the engine and other related components, resulting in higher repair costs in the long run.


To avoid these long-term effects, it is very important to promptly address code P0390 by diagnosing the problem, determining the root cause, and performing any necessary repairs or replacements.



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