P0394 Diagnostic Trouble Code: Camshaft Position Sensor “B” Circuit Intermittent/Erratic (Bank 2)

Fault code P0394 is called “Camshaft Position Sensor “B” Circuit Intermittent/Erratic (Bank 2)” but in different programs it may be called differently. This fault designation applies to all vehicles equipped with OBD-II.

Technical description and explained code P0394

The camshaft position sensor is an electronic device used in the engine to record the speed of the camshaft. This information is used by the engine control module (ECM) to control ignition and fuel injection.

P0394 Diagnostic Trouble Code: Camshaft Position Sensor "B" Circuit Intermittent/Erratic (Bank 2)

The camshaft position sensor monitors the camshaft for specific cylinder identification and determines the piston position. The sensor system consists of a rotating part, usually a disc, and a static part, the actual sensor.

When the engine is running, the high and low parts of the cogs cause the clearance to change with the sensor. A change in the gap causes a change in the magnetic field. And a change in the magnetic field causes a change in the voltage on the sensor.

When the crankshaft position sensor (POS) system fails. The camshaft position sensor provides different control of engine parts. By synchronizing the cylinder identification signals.

Automotive fault code P0394 is one of several common fault codes related to the camshaft position sensor (CPS). It means that the sensor signal is intermittent, exceeding the allowable parameters laid down by the vehicle manufacturer.

P0394 refers to sensor “B” Bank 2. Bank 2 is the side of the engine that does not contain cylinder 1.

Symptoms of vehicle malfunctions

The main signal that an error P0394 has occurred is the Malfunction Indicator Lamp (MIL) is also known as the CheckEngine Light.

It can also be warning signs such as:

  1. Check engine control lamp on the control panel will light up (the code will be recorded in the ECM memory as a fault).
  2. Decrease of engine power output.
  3. Ignition skips in the engine cylinders may occur. Also the car engine may run unstable.
  4. Floating revolutions, as well as attempts to stall at idle.
  5. The engine may stall or not start well.
  6. Increased fuel consumption.

The vehicle is likely to run with the fault code P0394. But it may be difficult to start, and there may be a drop in power and unstable engine operation. To avoid damage to other engine components when this code is detected, it is advisable to correct the fault as soon as possible.

Factors that can cause this error code

The error code P0394 can mean that one or more of the following problems have occurred:

  • The camshaft position sensor wiring harness is broken or shorted.
  • Electrical connection between the sensor and ECM may be bad.
  • Camshaft position sensor is defective.
  • Low battery charge level.
  • Defective starter.

On some models, low battery voltage or weak starter may cause camshaft position sensor code P0394.

How to fix or reset OBD-2 code P0394

Some suggested steps for troubleshooting and fix the error code P0394:

  1. Inspect wiring, looking for corrosion, poor connections, or worn insulation.
  2. Check the connector on the camshaft sensor. Look for corrosion and defects in the connector. Apply dielectric grease to the connection.
  3. Replace the camshaft position sensor.
  4. Test the condition of the battery. A low battery can cause a code to set.
  5. Check the starter for excessive traction, indicating weak recoil.

Often replacing the sensor will fix the P0394 error code, but not necessarily. Therefore, it is important to do a check of all items.

Diagnose and repair of problems

Error P0394 refers to an electrical circuit problem, but the camshaft position sensor should not be overlooked. The sensor itself can fail, but its replacement does not always solve the problem. Therefore, it is necessary to check the electrical circuit with a digital voltmeter as well.

Make sure that the connector on the sensor is secure. Also, inspect the wiring harness for damage. For example, damage from recent engine repairs, impact or rodent damage.

Check the sensor

Disconnect the sensor and measure the resistance. If it reads infinity, there is an open or short circuit. If it reads 0 ohms, you can tell that the sensor itself is defective.

It is best to use a digital oscilloscope to check the signal. But you can also get a rough estimate by putting the voltmeter in alternating voltage mode. The test should give at least 20 mV.

Electrical Inspection

Disconnect the ECM and CMP controller connectors, then place a short jumper on the CMP connector terminals. A small paper clip or wire may be used for this purpose.

On the ECM controller side, check the resistance in the circuit itself. It should be less than 0.1 ohm. If it is more, ECM will not be able to detect the signal. Therefore, you need to look for a broken wire or corrosion.

Remove the jumper and check the circuit for a break, if there is resistance, a short circuit has most likely occurred. Water in the connector can easily cause this. Check for a ground fault by taking one of the leads and connecting it to “ground” or the negative battery terminal.

If no problems are found in the CPS sensor or its wiring, P0394 is probably just an auxiliary fault code. Pay attention to a jumped timing belt. There may also be a faulty signal, crankshaft position sensor circuit, or engine ignition misfire.

On which vehicles does this problem occur most frequently

Fault code P0394 can occur on different vehicles but there are statistics on which brands this occurs most often. Here is a list of some of them:

  • Chrysler (Town and Country)
  • Dodge (Caravan, Journey)
  • Ford (F-150, Taurus)
  • Jeep (Grand Cherokee, Wrangler)
  • Toyota (Camry)

Fault code P0394 can sometimes be found with other errors. The most common are the following: P0340, P0341, P0342, P0343, P0345, P0346, P0347, P0348, P0349, P0365, P0366, P0367, P0368, P0369, P0390, P0391, P0392, P0393.

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