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DTC codes / P01xx · Fuel and air metering / P01C5

P01C5Fuel Pressure Sensor A Circuit Low

P01C5 indicates that the powertrain control module (PCM) has detected a low voltage signal on the fuel pressure sensor A circuit, which typically measures fuel pressure in the high-pressure fuel system on gasoline direct-injection engines. The PCM compares the sensor's output to expected values and sets this code when the signal falls below the calibrated minimum for a specified time, indicating a short to ground, an open circuit, or a faulty sensor.

SystemPowertrain
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyIntermediate
AreaFuel and air metering

Symptoms you may notice

  • Illumination of the check engine light, often with no other noticeable symptoms
  • Reduced engine power or limp mode due to the PCM limiting fuel pressure
  • Rough idle, misfires, or stalling, especially when the engine is cold or under load
  • Difficulty starting or extended cranking times
  • Poor fuel economy or black smoke from the exhaust if the engine runs rich

Common causes, most likely first

  1. Faulty fuel pressure sensor A, internally shorted or failed
  2. Damaged or corroded wiring harness to the sensor, including chafed wires or loose pins
  3. Poor electrical connection at the sensor or PCM connector
  4. Open circuit or high resistance in the sensor ground or signal return circuit
  5. Low fuel pressure from a weak high-pressure fuel pump or a clogged fuel filter, causing the sensor to read low
  6. PCM internal fault, though this is rare and should be diagnosed last

How to diagnose and fix it

  1. Connect a scan tool and record freeze-frame data and fuel pressure sensor voltage to confirm the low signal
  2. Visually inspect the sensor, wiring, and connectors for damage, corrosion, or loose pins, and repair as needed
  3. Measure reference voltage and ground at the sensor connector with a multimeter to verify the circuit integrity
  4. Check for continuity and resistance in the signal wire between the sensor and PCM, looking for opens or shorts
  5. Test the fuel pressure sensor with a known-good sensor or perform a voltage output test to confirm failure
  6. If the sensor tests bad, replace it and clear the code, then verify fuel pressure readings return to normal
  7. If the circuit and sensor are good, check fuel pump operation and pressure, and inspect the PCM for faults

Don't overlook the fuel pump driver module

  • A low signal from the fuel pressure sensor often results from a failing fuel pump control module that reduces pump output, not just a bad sensor.
  • Corrosion inside the sensor connector can mimic a failed sensor, so always perform a voltage drop test on the ground circuit before replacing parts.
  • On some vehicles, a low fuel pressure sensor code can be set by a restricted fuel filter that causes actual low pressure, so verify mechanical pressure with a gauge.
  • The PCM may set this code intermittently if the sensor signal wire is routed too close to high-voltage ignition components, causing electrical interference.
  • After replacing the sensor, some vehicles require a fuel pressure sensor relearn procedure with a scan tool to prevent the code from returning.

Can I keep driving with P01C5?

It is not recommended to drive with this code because low fuel pressure can cause stalling, misfires, or a sudden loss of power, especially under load. If you must drive, avoid heavy acceleration and high speeds, and have the vehicle diagnosed as soon as possible.

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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