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P0394 code definitionWhen an OBD-II scanner detects the P0394 code, it indicates that the PCM has detected an intermittently incorrect voltage reading from the camshaft sensor circuit B in engine bank 2. What the P0394 code meansIn order for the engine control module, or ECM, to control the fuel injection and ignition within the engine, it requires data regarding the rate at which the camshaft is spinning. This data is provided by the camshaft position sensor, which reads the change in the magnetic field of the camshaft operation and translates that information into voltage. If the voltage does not match what the manufacturer’s specifications say that it should be for the current circumstances, the PCM will assume that there is an issue with the sensor and store the P0394 code. What causes the P0394 code?The camshaft and sensor are both made up of multiple parts that could create an issue for the voltage reading. Therefore, the root cause of the P0394 could be any of the following:
What are the symptoms of the P0394 code?The symptoms of the P0394 code may include a rough idle, difficulty accelerating, difficulty starting the engine, total engine stall, and the illumination of the Check Engine light. How does a mechanic diagnose the P0394 code?Once the P0394 code has been verified with the scanner, the technician should perform a visual inspection of all the wiring, connectors, and other electrical components. If any damaged elements appear, they should be replaced, reconnected, or repaired as necessary. The mechanic should then clear the P0394 code from the PCM memory, and retest the system. If the code returns, they will then move on to other repairs to address issues within the camshaft position sensor. Common mistakes when diagnosing the P0394 codeMost often, technicians will assume that the issue lies with a faulty sensor, and replace the part without performing a thorough diagnosis on the entire system. OEM sensor components don’t fail as frequently as other issues, and the code pertains to the entire circuit, which could indicate a fault at many other specific parts. How serious is the P0394 code?If the P0394 code is being detected, it indicates a very serious issue that should be addressed right away. The problem relates directly to how well the ignition and fuel injection functions operate, and can have significant effect on the vehicle overall. What repairs can fix the P0394 code?In order to repair the cause of the P0394, there are many things that a mechanic should do in order to properly diagnose and address the issue. These steps may include:
After each possible repair is performed, it is important to clear the code from the PCM and retest the system, to confirm that the fix did or did not address the issue. Manufacturers recommend replacing crankshaft components at the same time that any camshaft components are replaced. These components work as a team, and perform better when they have similar amounts of wear. Need help with a P0394 code?YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230. Check Engine Light trouble codes P0394 We recommend Torque Pro If a code P0394 accompanies a malfunction indicator lamp (MIL) in your vehicle, it means that the powertrain control module (PCM) has detected a problem with the exhaust camshaft position sensor (or circuit) for engine bank one. Bank 2 represents the bank of the engine that does not contain the number one
cylinder. Sensor B indicates that the malfunction is occurring with the camshaft position sensor circuit that pertains to the exhaust camshaft. The PCM uses input signals from the camshaft sensor/s and the crankshaft sensor to monitor the position and revolutions per minute (RPM) of these vital engine components, manage timing fluctuations, and map fuel delivery strategy. Clearly, variations in engine configuration will dictate the number of camshaft sensors that are required. For
instance; an overhead valve engine will typically be equipped with a single camshaft sensor because the engine has only one camshaft. An overhead cam, four-cylinder engine will likely have only one camshaft sensor as well (because it has only one engine bank), but an overhead cam, V6 requires at least two camshaft sensors (one per engine bank). Likewise, a dual overhead cam, V8 engine will require four camshaft sensors because there are two engine banks with two camshafts in each bank. Each
camshaft sensor has a circuit (or circuits) dedicated to providing the PCM with individual input signal/s. Camshaft position and camshaft speed are compared to the speed and position of the crankshaft in order to prevent engine damage and calculate ignition timing and fuel delivery strategy. Since the camshaft/s turn at half the speed of the crankshaft, it is critical that the PCM is able to distinguish between engine intake and exhaust stokes (rotations). This is also accomplished with the
camshaft position sensor. The most common camshaft position sensor design utilizes an electromagnetic hall effect sensor positioned in very close proximity (usually only several thousandths of an inch) from a circuit completing engine ground. In most cases, either a reluctor ring (with precisely machined teeth) is affixed to the camshaft pulley or there are cogs stringently integrated into the camshaft itself. The camshaft position sensor is mounted so that these teeth/cogs pass very closely to its magnetic end. As the camshaft rotates, the raised areas complete an electromagnetic circuit. When the indentations (between the teeth pass) pass the camshaft sensor, the circuit is briefly interrupted. Since the camshaft rotates very quickly, the process of repeatedly completing and interrupting the circuit occurs in milliseconds. This progression of completing and interrupting the camshaft position sensor circuit produces a waveform pattern. This pattern is recognized by the PCM as camshaft position. All of the camshaft position sensors and the crankshaft sensor function in a similar manner. When the engine is running, the PCM constantly compares input signals from the camshafts and the crankshaft. If the camshaft position is not within a specified degree of variation from the crankshaft and other camshafts, under certain circumstances, for a set period of time, a P0394 code will be stored and a MIL may be illuminated. Typically, when this code is set, the engine will continue to start and run but will fail to perform at an efficient level. What are the common causes of code P0394?
What are the symptoms of code P0394?
How do you troubleshoot code P0394?Regardless of the code and the system affected, the word “Intermittent” refers to the fact that there is a sporadic, unpredictable, or, well, intermittent fault in that system. The most likely causes of codes that relate to intermittent faults include poor connections in both live and ground circuits, as well defective switches, relays, and sensors. Intermittent faults can be extremely difficult to trace and fix, since code readers generally do not specify in which part of the circuit the problem lays. For instance, the fault could be an intermittent interruption of the reference voltage (power supply), or, as often happens, the problem could be an intermittent break in the signal voltage to the PCM (Powertrain Control Module) due to a failing sensor, wiring issues, or defective electrical connector(s). Note that the word “intermittent” often means different things to different applications; some systems will set a code the first time an intermittent fault occurs, while others will only do so after several failure cycles. In some cases, it may be necessary to allow the fault to worsen before an accurate and definitive repair can be made. Before attempting to diagnose a code P0394, I would need a suitable diagnostic scanner, a digital volt/ohmmeter (DVOM), possibly an oscilloscope, and access to All Data DIY. I like to perform a visual inspection of all system related wiring harnesses and connectors before beginning any testing. Wiring circuits, electrical sensors, and/or connectors that have been contaminated with engine oil, coolant, or power steering fluid should be examined carefully for damage. Petroleum based fluids may break down the protective insulation on wiring and lead to shorted or open circuits and a stored P0394. This is also a great time to load test the battery, check battery terminal ends and cables, and alternator output. Now, connect the scanner to the vehicle diagnostic port and retrieve all stored trouble codes and freeze frame data (if available). I like to write this information down as it tends to help if the code proves to be intermittent. Some scanners also feature a DVOM and an oscilloscope with integrated test leads. If you can obtain this type of scanner, it will be your best bet for diagnosing this code. Proceed by testing voltage and ground signals at the camshaft sensor in question. Most OBD-II equipped vehicles utilize a five-volt reference as a base, but check manufacturer’s specifications for your vehicle. There should also be a ground signal. A third circuit (known as a signal circuit) supplies a signal to the PCM. There may also be other output signal wires but this is a basic overview. Again, check the wiring diagram (found on All Data DIY) for your vehicle. If the reference voltage and ground circuits are within manufacturer’s specifications, proceed to the next step. Disconnect the electrical connector from the camshaft sensor in question and test it following manufacturer’s recommendations, using the DVOM. If the resistance values of the sensor fail to comply with manufacturer’s specifications, replace the sensor. If all internal sensor circuit resistance values are in line with specs, proceed to the next step. Reconnect the camshaft sensor in question and attach the positive test lead of the oscilloscope to the signal output wire. Connect the negative lead to the sensor ground circuit. Turn the oscilloscope on and select the appropriate voltage setting. With the engine running, observe the waveform pattern on the oscilloscope. Look for unexpected spikes or glitches in the waveform pattern. If spikes or glitches are observed, carefully wiggle the wiring harness and connector for the sensor in question to try and determine whether the problem is a loose connection or a defective sensor. Also look for missing voltage blocks in the waveform pattern. If there are missing blocks, suspect a broken or worn reluctor wheel or cog. Also check the magnetic tip of the camshaft sensor for excessive metallic debris and clean it as necessary. If the waveform seems normal, proceed to the next step. Reconnect the test leads of the oscilloscope to the same circuits near the PCM connector. Observe the waveform pattern. If there are variations in the waveform pattern, as it was seen when the test leads were connected near the sensor, suspect an open or shorted circuit between the camshaft position sensor connector and the PCM connector. Disconnect the connectors from all related controllers and begin testing individual circuits with the DVOM. Shorted or open circuits must be replaced. If the waveform pattern appears as it did when the test leads were connected near the sensor, suspect a defective PCM or a programming error. Codes Related to P0394
This is not an exhaustive list of related codes. Help Us Help YouPlease comment below describing your issue as well as the specifics of your vehicle (make, model, year, miles, and engine), and one of our mechanics will respond as soon as possible. For an expedited response within 24 hours, we appreciate a $9.99 donation via the payment button below. Where is camshaft position sensor B located?The camshaft position sensor notes the rate at which the camshaft is spinning, and helps the car's computer control things like fuel injection and engine timing. Note that the “B” means that this sensor is located in the exhaust side of the cylinder head.
How do I fix P0394 code?What repairs can fix the P0394 code?. Inspecting and repairing all electrical components during the initial diagnosis.. Replacing a faulty camshaft position sensor.. Addressing a leak in oil or engine fluids, and replacing any wiring or electrical components that were affected by the leak.. What side is camshaft sensor bank 2?Registered. There's two cam sensors. One of the drivers rear of the head, the other on the passenger rear of the head. it's bank two, which is typically cylinders 2&4 which is the drivers side.
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P0394 camshaft position sensor b circuit bank 2 location
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