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DTC codes / P03xx · Ignition system and misfire / P0349

P0349Camshaft Position Sensor 'A' Circuit Intermittent

P0349 means the engine computer has detected an intermittent fault in the camshaft position sensor 'A' circuit, so the signal drops out or becomes erratic rather than failing completely. The computer sets this code when the camshaft signal is missing or inconsistent for a brief period while the engine is running, often logging it alongside other cam or crank codes.

SystemPowertrain
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyIntermediate
AreaIgnition system and misfire

Symptoms you may notice

  • The check engine light may be the only thing you notice, especially if the interruption is brief and the engine management system compensates.
  • The engine may stumble, hesitate, or misfire intermittently, particularly during acceleration or at steady cruise.
  • You might experience hard starting or a crank-no-start condition that comes and goes without warning.
  • The engine may stall unexpectedly at idle or when coming to a stop, then restart normally.
  • A noticeable loss of power or reduced fuel economy can occur if the intermittent signal disrupts fuel and spark timing.
  • Some vehicles may enter limp mode or show a flashing check engine light during the intermittent fault.

Common causes, most likely first

  1. A damaged or chafed wire in the camshaft sensor circuit, often where the harness bends near the sensor or passes close to hot or moving components.
  2. Corroded, loose, or backed-out terminals at the camshaft sensor connector or at the engine computer connector.
  3. An internally failing camshaft position sensor that drops its signal when hot or vibrates intermittently.
  4. Metal debris or sludge buildup on the sensor tip or the reluctor wheel, disturbing the magnetic field and causing a weak signal.
  5. A worn or damaged reluctor wheel, camshaft tone ring, or timing chain/belt that has jumped, causing the signal to become erratic.
  6. Electrical interference from a failing ignition component or a poor ground connection shared with the sensor circuit.
  7. A faulty engine computer, though this is rare and should only be considered after all other causes are ruled out.

How to diagnose and fix it

  1. Inspect the camshaft sensor connector and the full wiring harness for chafing, corrosion, or loose pins, and repair any damage found.
  2. Check the sensor mounting bolt and air gap if adjustable, and clean any metal debris or sludge from the sensor tip and reluctor wheel.
  3. Use a scan tool to watch the camshaft sensor signal live while wiggling the harness and tapping the sensor to reproduce the intermittent dropout.
  4. Measure the sensor circuit with a multimeter or oscilloscope to check for voltage drops, shorts to ground, or an erratic waveform during the fault.
  5. Swap the camshaft sensor with a known-good unit only if the wiring and signal tests point to the sensor, then clear the code and retest.
  6. Verify the timing chain or belt is not stretched or jumped by checking camshaft-to-crankshaft correlation with a scan tool or oscilloscope.
  7. Clear the code after repairs and perform a road test with the scan tool recording to confirm the intermittent signal is gone and the code does not return.

Intermittent cam codes often hide wiring faults

  • A loose or corroded ground connection shared by the camshaft sensor and other engine sensors can create an intermittent signal that mimics a failing sensor.
  • Heat and vibration frequently cause a sensor to drop out only when the engine is hot, so testing a cold engine may show no fault at all.
  • Aftermarket sensors with incorrect magnetic strength or air gap are a common cause of repeat P0349 codes even after replacement.
  • A stretched timing chain can cause the camshaft signal to become erratic without setting a timing correlation code first, so always check cam-crank sync.
  • The code can be set by a brief electrical glitch that leaves no permanent fault, so clearing it and road testing before replacing parts is a valid first step.

Can I keep driving with P0349?

You can usually drive the vehicle to a repair shop if the engine runs smoothly and the check engine light is steady, but avoid heavy acceleration or long trips until the fault is diagnosed. If the engine stalls, misfires badly, or the check engine light flashes, stop driving and have the vehicle towed to prevent damage to the catalytic converter.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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