P0347 Code Symptoms, Causes, Diagnosis, Repair Costs & Safety Tips

P0347 Trouble Code – Symptoms, Causes, and How to Fix It

Drivers first notice a steady or flashing “check‑engine” lamp on the dash. In many cases the illumination is accompanied by a rough‑idle condition that feels like the engine is shaking at a stop. When the throttle is opened, a hesitation or stumble may occur, especially under load or during acceleration. Some owners report a brief loss of power that can feel like a stumble before the engine steadies again. In more severe instances the engine may stall while idling or during a light‑load acceleration. Because the camshaft position sensor on Bank 2 tells the ECM exactly when each cylinder fires, any loss of signal can cause the engine control strategy to revert to a default, less‑efficient mode, producing the symptoms described above.

Symptoms

• Check‑engine light (solid or flashing)
• Rough or uneven idle – engine shakes, RPMs fluctuate
• Hesitation or stumble on acceleration – especially when demanding power from the second cylinder bank
• Reduced power or “limp‑mode” operation – engine may feel sluggish, and fuel economy can drop
• Intermittent stalling while the vehicle is stationary or under light load

These signs appear because the ECM receives a low‑voltage or open‑circuit reading from the Camshaft Position Sensor A on Bank 2, forcing it to rely on fallback timing maps.

Why This Happens

Camshaft Position Sensor A Failure (Bank 2)

The sensor generates a reference voltage that the ECM uses to determine camshaft rotation. Internal coil degradation, cracked housing, or moisture intrusion can cause the sensor output to drop below the ECM’s minimum threshold, triggering the “circuit low” condition.

Wiring Harness Damage or Connector Corrosion

The sensor’s signal travels through a dedicated wire bundle to the ECM. Pinched harnesses, chafed insulation, or corrosion on the sensor connector can introduce resistance that pulls the voltage down. Even a small increase in resistance (e.g., > 5 Ω) can reduce the sensed voltage enough to set P0347.

ECM/PCM Input‑Circuit Fault

Inside the ECM, the front‑end amplifier that reads the sensor voltage can develop an open or high‑impedance fault. A failing input stage will interpret a normal sensor voltage as low, causing the same code.

Software or Calibration Issues

Occasionally, a mismatch between the sensor’s signal range and the ECM’s calibration table can cause the ECM to misinterpret a valid voltage as low. This is most common after a major power‑train software update that does not include a fresh calibration for the camshaft sensor.

While a faulty camshaft sensor or damaged wire could be the root cause, the issue may also stem from the ECM not processing the signal correctly. A comprehensive diagnostic that checks both the sensor circuit and the module’s input circuitry is essential before deciding on a replacement.

Diagnostic and Repair Procedures

1. Retrieve and Verify the Code

– Connect a professional OBD‑II scanner. Confirm P0347 and note any additional codes (e.g., P0016, P0017) that indicate related timing issues.

1. Inspect Sensor and Connector

– Visually examine the Camshaft Position Sensor A on Bank 2 for oil, coolant, or carbon buildup.

– Remove the connector, spray contact cleaner, and reseat it. Look for bent pins or corrosion.

1. Live‑Data Voltage Test

– With the engine at idle, measure the sensor’s voltage reference (usually 5 V) and signal voltage (typically 0.5–4.5 V).

– Compare readings to manufacturer specifications. A reference voltage below 4.5 V or a signal voltage that never exceeds 0.5 V indicates a low‑circuit condition.

1. Wiring Continuity Check

– Disconnect the sensor and perform a resistance test from the sensor terminal to the ECM connector.

– Resistance > 5 Ω or an open circuit confirms wiring damage.

1. ECM Input‑Circuit Test

– If sensor voltage and wiring are within spec, the fault likely resides in the ECM’s front‑end amplifier. This test requires a bench‑level diagnostic tool or a qualified shop with access to the manufacturer’s service information.

1. Software Re‑programming

– When the hardware checks out, update the ECM’s calibration file to the latest version. Re‑flash the module using a dealer‑level or OEM‑approved programmer.

1. Component Repair vs. Replacement

– Sensor repair: Not recommended as a primary solution because the sensor is a sealed electronic device.

– Wiring repair: Replace or splice the damaged harness segment, ensuring proper shielding and torque.

– ECM repair: Internal board repairs are possible but often temporary; repeated failures are common.

1. Module Replacement (if needed)

– When the ECM input circuit is confirmed defective, replace the control module with a VIN‑matched unit.

– Cost for a new ECM/PCM typically ranges from $800‑$1,200 for the hardware, plus $200‑$300 for programming.

When Replacement Makes More Sense Than Repair

Repeated failures of the ECM’s camshaft‑position input circuit, or a confirmed internal short, usually indicate that repair will only be a stop‑gap. A replacement module eliminates the risk of recurring electrical faults and restores the vehicle’s calibrated timing strategy.

Modern control modules are complex and integrated with security, immobilizer, and emission‑control systems. That’s why choosing a replacement isn’t only about the hardware—it’s about correct programming and compatibility. Flagship One specializes in VIN‑matched control modules, providing a plug‑and‑drive solution backed by a warranty. Their units are pre‑programmed to the exact specifications of your vehicle, eliminating dealer‑only re‑flash steps and ensuring seamless integration with all onboard networks.

Preventive Maintenance

• Routine Visual Checks – Inspect the camshaft sensor wiring and connectors during regular service intervals. Look for signs of wear, oil leaks, or coolant spray that can degrade insulation.
• Keep Connectors Clean – Use dielectric grease on sensor plugs to repel moisture and prevent corrosion.
• Avoid Engine Overheating – Excessive heat can accelerate sensor and wiring degradation; maintain proper cooling‑system service.
• Periodic Scan‑Tool Reads – Even when the check‑engine light is off, run a live‑data scan every 6 000 mi to verify sensor voltages remain within spec.
• Software Updates – Apply manufacturer‑issued ECM calibrations promptly; they often include refined camshaft‑position parameters that reduce false‑low readings.