What Does It Mean?
This is a generic powertrain diagnostic trouble code (DTC), meaning it covers all makes/models from 2003 onward. The code appears more commonly on Dodge, Chrysler, Ford, Honda, Jeep, BMW, and Acura vehicles, but any vehicle brand can be affected. Specific troubleshooting steps vary by vehicle.
These vehicles may have a single camshaft in-block or a single overhead camshaft (SOHC) or dual (DOHC), but this code is strictly concerned with the fact that the incoming signal from the camshaft position sensor(s) for Bank 1 is missing at a time when it shouldn’t be. It’s an electrical circuit fault and is intermittent in nature. It’s not present all the time. Bank #2 is the engine bank that does not contain cylinder #1.
The PCM uses the camshaft position sensor to tell it when the crankshaft sensor signal is correct, when a given crankshaft position sensor signal is timed to cylinder #1 for timing, and it is also used for fuel injector timing/injection start.
P0340 or P0341 codes may also be present alongside P0349. The only difference between these 3 codes is the duration of the issue and the type of electrical problem experienced by the sensor/circuit/engine controller. Troubleshooting steps may vary by manufacturer, camshaft position sensor type, and wire colors.
Symptoms
Symptoms of a P0349 engine code may include:
Check Engine Light illuminated
Intermittent misfiring or surging
Intermittently stalls but restarts immediately
Potential Causes
Typically, causes for this code include:
Intermittent open in the camshaft position sensor power circuit
Intermittent short to ground in the camshaft position sensor power circuit
Intermittent open in the ground circuit to the camshaft position sensor
Intermittent open in the camshaft position sensor signal circuit
Intermittent short to 5 volts in the signal circuit to the camshaft position sensor
Intermittent short to ground in the camshaft position sensor signal circuit
Damage to the camshaft position sensor tone ring
Crankshaft position sensor occasionally producing intermittent signals
Diagnostic and Repair Procedures
A good starting point is always researching a Technical Service Bulletin (TSB) for your specific vehicle. The vehicle manufacturer may have a PCM flash/reprogram to address this issue, and it’s worth checking before discovering you’ve taken a long/wrong path.
Next, locate the camshaft and crankshaft position sensors on your specific vehicle. Once located, visually inspect the connectors and wiring. Look for chafing, rubbing, bare wires, burns, or melted plastic. Disconnect the connectors and carefully inspect the terminals (the metal parts) inside the connectors. See if they appear corroded, burnt, or perhaps greenish compared to the normal metal color you’re used to seeing. You can get electrical contact cleaner at any auto parts store if terminal cleaning is needed. If not available, find 91% rubbing alcohol and a soft plastic-bristled brush to clean them. Then let them air dry, get some dielectric silicone compound (same as used for light bulb sockets and spark plug wires), and apply a small amount where the terminals make contact.
If you have a scan tool, clear the diagnostic codes from memory and see if this code returns. If not, the connections were likely your problem.
If the code returns, we’ll need to test the sensor and its associated circuits. The next steps will be determined by the type of sensor you have: Hall effect or magnetic sensor. You can usually tell which you have based on the number of wires coming from the sensor. If there are 3 wires from the sensor, it’s a Hall effect sensor. If it has 2 wires, it will be a magnetic pickup type sensor.
Hall Effect Sensor
If it’s a Hall effect sensor, disconnect the harness going to the camshaft and crankshaft position sensors. With a digital voltmeter (DVOM), test the 5V power circuit going to each sensor to ensure it has power (red wire to 5V power circuit, black wire to good ground). If there’s no 5 volts at the sensor, repair the wiring from the PCM to the sensor, or possibly a faulty PCM.
If that’s okay, with a DVOM, check that you have 5V on each signal circuit going to each sensor to ensure it has a signal circuit (red wire to sensor signal circuit, black wire to good ground). If there’s no 5 volts at the sensor, repair the wiring from the PCM to the sensor, or possibly a faulty PCM.
If that’s okay, verify you have a good ground at each sensor. Connect a 12V test light and touch the other end of the test light to the ground circuit going to each sensor. If the test light doesn’t illuminate, that would indicate the circuit problem. If it does light up, wiggle the wire harness going to each sensor to see if the test light flickers, indicating an intermittent connection.
Magnetic Pickup Sensor
If it’s a magnetic pickup type sensor, we can check the sensor itself to see if it’s functioning properly. We’ll test it for:
Resistance
A/C voltage output
Short to ground
With the sensor disconnected, connect both wires of your ohmmeter to the 2 terminals of the camshaft/crankshaft position sensor. Read the ohms resistance and compare it to your vehicle’s specifications: typically 750 – 2000 ohms. While still on ohms, disconnect 1 wire of your ohmmeter from the sensor and connect it to a good vehicle ground. If you get an ohms reading other than infinite or OL, the sensor has an internal short to ground. Remember not to touch the metal part of the wires with your fingers, as this could affect your readings.
Reconnect both wires of your DVOM to the 2 terminals of the camshaft/crankshaft position sensor. Set your meter to read A/C voltage. While cranking the engine, read the a/c voltage output on your DVOM. Compare to manufacturer specifications for your vehicle. A good rule of thumb is typically 0.5 V AC.