Faulty camshaft position sensor 'A' (internal short or open); Damaged or corroded wiring in the sensor circuit (open, short to ground, or high resistance); Loose or corroded electrical connector at the sensor or ECM; Metal debris or damage on the sensor tip or reluctor wheel; ECM internal fault affecting the sensor reference voltage or signal processing; Aftermarket or incorrect sensor installed previously

DTC codes / P03xx · Ignition system and misfire / P0347

P0347Camshaft Position Sensor 'A' Circuit Low

Q: What does code P0347 mean?

Camshaft Position Sensor 'A' Circuit Low. P0347 indicates that the engine control module (ECM) has detected a low-voltage condition on the camshaft position sensor 'A' circuit, which is responsible for reporting the camshaft's position to the computer. The ECM expects a signal that toggles between high and low voltage as the camshaft rotates, but the circuit is staying below the expected threshold for too long. This can disrupt fuel injection and ignition timing, leading to poor performance or a no-start condition.

P0347 indicates that the engine control module (ECM) has detected a low-voltage condition on the camshaft position sensor 'A' circuit, which is responsible for reporting the camshaft's position to the computer. The ECM expects a signal that toggles between high and low voltage as the camshaft rotates, but the circuit is staying below the expected threshold for too long. This can disrupt fuel injection and ignition timing, leading to poor performance or a no-start condition.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaIgnition system and misfire

Symptoms you may notice

Illuminated check engine light, often with no other noticeable symptoms
Engine may crank but fail to start, or start and stall immediately
Rough idle or misfiring due to incorrect timing signals
Reduced engine power or hesitation during acceleration
Poor fuel economy from inefficient combustion
Intermittent stalling while driving or at stops

Common causes, most likely first

Faulty camshaft position sensor 'A' (internal short or open)
Damaged or corroded wiring in the sensor circuit (open, short to ground, or high resistance)
Loose or corroded electrical connector at the sensor or ECM
Metal debris or damage on the sensor tip or reluctor wheel
ECM internal fault affecting the sensor reference voltage or signal processing
Aftermarket or incorrect sensor installed previously

How to diagnose and fix it

Perform a visual inspection of the sensor, connector, and wiring for obvious damage or corrosion
Check for technical service bulletins (TSBs) or recalls related to the camshaft sensor circuit for the specific vehicle
Use a digital multimeter to measure reference voltage (typically 5V or 12V) at the sensor connector with the key on
Test the sensor signal circuit for continuity and shorts to ground or power, wiggle-testing the harness
Replace the camshaft position sensor with a known-good OEM part if voltage tests indicate a faulty sensor
Clear the diagnostic trouble codes (DTCs) and perform a road test to verify the repair
If the code persists, diagnose the ECM and its connections as the last step

Don't overlook the sensor reluctor wheel

A common oversight is ignoring the reluctor wheel or tone ring on the camshaft, which can accumulate metal shavings or become damaged, causing a low signal even with a new sensor.
P0347 can be set by a poor ground connection at the sensor or ECM, so checking ground integrity is as important as checking the signal wire.
In some vehicles, a failing camshaft sensor may not prevent the engine from running because the ECM can default to a limp mode using the crankshaft sensor, masking the severity.
Aftermarket sensors are a frequent cause of repeat P0347 codes; always verify the sensor's resistance and signal output against factory specifications.
A low voltage on the camshaft sensor circuit can sometimes be caused by a short to ground in a related circuit, such as the crankshaft sensor wiring, due to shared harness routing.

Can I keep driving with P0347?

It is not advisable to continue driving with P0347 because the engine may stall unexpectedly or fail to start, and prolonged driving with incorrect timing can damage the catalytic converter. If the vehicle is driveable, limit travel to a short distance to a repair shop and avoid high speeds or heavy loads.

Tools that help

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