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DTC codes / P01xx · Fuel and air metering / P01C6

P01C6Fuel Pressure Sensor A Circuit High

P01C6 indicates that the powertrain control module has detected an abnormally high voltage on the signal circuit for Fuel Pressure Sensor A, which typically measures fuel rail pressure on a gasoline direct-injection engine. The sensor's output voltage is above the expected range for the current operating conditions, so the computer flags the circuit as high.

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-home mode triggered by the PCM
  • Rough idle, hesitation, or stumbling during acceleration
  • Hard starting or extended cranking before the engine fires
  • Poor fuel economy or an overly rich exhaust smell
  • In rare cases, the engine may stall or refuse to start

Common causes, most likely first

  1. A short to voltage on the sensor signal wire, often from chafed insulation against a power wire
  2. A faulty fuel pressure sensor A that internally shorts its signal output to a higher voltage
  3. Corroded, pushed-back, or loose terminals at the sensor connector or PCM connector
  4. A poor sensor ground connection, causing the signal to float high relative to the PCM reference
  5. A failed or leaking fuel pressure regulator that allows rail pressure to exceed the sensor's normal range
  6. A restricted fuel return line or a blocked fuel filter that raises pressure beyond specification
  7. A PCM internal fault biasing the signal circuit, though this is the least common cause

How to diagnose and fix it

  1. Connect a scan tool and record the fuel pressure sensor A voltage with key on, engine off and again at idle to confirm the high reading
  2. Visually inspect the sensor connector and the harness run for chafing, corrosion, or contact with hot or moving components
  3. Measure reference voltage and ground at the sensor connector with a digital multimeter to verify the PCM is supplying the correct 5-volt reference and a clean ground
  4. Back-probe the signal wire and compare its voltage to the scan tool data to rule out a wiring fault between the sensor and PCM
  5. Check fuel rail pressure with a mechanical gauge and compare it to the sensor's reported value to determine whether the sensor or the actual pressure is wrong
  6. If the signal circuit is intact and pressure is normal, replace the fuel pressure sensor A and clear the code
  7. If pressure is genuinely high, inspect the fuel pressure regulator and return line, repair as needed, then clear codes and verify the repair with a road test

Why a high fuel pressure reading can mislead

  • A shorted sensor signal wire can read high even when actual fuel pressure is perfectly normal, so always verify pressure mechanically before condemning the sensor.
  • A bad ground at the sensor connector will make the signal voltage climb relative to the PCM reference, mimicking a short to voltage and fooling parts-swappers.
  • On some direct-injection engines, a failing high-pressure fuel pump can spike rail pressure and set this code without any sensor fault at all.
  • The PCM may set P01C6 intermittently from vibration-related harness chafing, so wiggle-test the harness while watching live data before replacing parts.
  • Clearing the code without repairing the root cause often leads to a repeat visit, because the PCM re-runs the fuel pressure rationality test on the next cold start.

Can I keep driving with P01C6?

You can usually drive the vehicle to a repair shop, but avoid heavy acceleration and towing because a genuinely high fuel pressure condition can damage the high-pressure fuel pump and injectors. If the engine enters limp mode or stalls, stop driving and have the vehicle towed.

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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