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DTC codes / P03xx · Ignition system and misfire / P03DE

P03DECylinder 8 Pressure Sensor Circuit High

P03DE indicates that the powertrain control module has detected an abnormally high voltage signal from the cylinder 8 pressure sensor circuit, which is used to monitor combustion pressure for that specific cylinder. The computer expects the sensor's output to stay within a calibrated range, and a high reading typically means the signal wire is shorted to voltage or the sensor has failed internally.

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

Symptoms you may notice

  • Illumination of the check engine light, often with no other noticeable symptoms
  • Rough running or misfire under load if the faulty sensor affects fuel or ignition timing calculations
  • Reduced engine power or limp mode in some vehicles as a protective measure
  • Poor fuel economy due to incorrect combustion pressure feedback
  • Intermittent hesitation or stumble during acceleration
  • Possible abnormal engine noise if the pressure sensor is physically damaged

Common causes, most likely first

  1. Short to voltage in the signal wire between the cylinder 8 pressure sensor and the PCM
  2. Faulty cylinder 8 pressure sensor internally shorted
  3. Damaged or corroded connector at the sensor or PCM
  4. Water intrusion or contamination in the sensor circuit
  5. PCM internal fault causing a high voltage reading
  6. Aftermarket or incorrect sensor installed previously
  7. Wiring harness chafed against a hot or moving component

How to diagnose and fix it

  1. Connect a scan tool and verify the P03DE code is current, then check for any related codes and freeze-frame data
  2. Visually inspect the cylinder 8 pressure sensor, its connector, and the wiring harness for damage, corrosion, or loose pins
  3. Measure the sensor reference voltage and ground at the connector with a multimeter to confirm proper supply
  4. Backprobe the signal wire and check for a short to voltage with the sensor disconnected; repair any wiring fault
  5. Swap the cylinder 8 pressure sensor with a known-good one from another cylinder (if accessible) to see if the code moves
  6. If the sensor is faulty, replace it with an OEM-quality part and clear the codes
  7. If all external checks pass, test the PCM circuit or consult a dealer for PCM diagnostics

Cylinder pressure sensor circuit pitfalls

  • A high voltage reading often comes from a shorted signal wire rather than a failed sensor, so always check the harness before replacing parts.
  • Some vehicles use cylinder pressure sensors for misfire detection and fuel balancing; a faulty sensor can cause drivability issues that mimic ignition or fuel problems.
  • The connector at the sensor is prone to oil or coolant contamination, which can create a high-resistance short and set this code intermittently.
  • If the sensor is swapped to another cylinder and the code follows, the sensor is at fault; if the code stays on cylinder 8, the wiring or PCM is suspect.
  • This code is rarely caused by mechanical engine problems, so avoid unnecessary teardown until the electrical circuit is fully ruled out.

Can I keep driving with P03DE?

You can usually drive the vehicle with this code, but avoid heavy acceleration or towing until it is diagnosed, as the fault may cause poor running or reduced power. If the check engine light starts flashing or the engine runs very rough, stop driving and seek professional help.

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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