P03C7

Code

Generic P — Powertrain

Cylinder 6 Pressure Sensor Circuit

Brand: Generic

Type: P — Powertrain

Views: UK: 26 EN: 26 RU: 28

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MIL / Check Engine Light illuminated
Possible rough idle or cylinder-specific misfire if the ECM uses the sensor for cylinder control
Reduced engine performance or hesitation (depending on system reliance)
Difficulty starting or poor fuel economy in some systems
Stored misfire codes for cylinder 6 (may appear with this code)
No obvious drivability symptoms if sensor is used only for diagnostics

Read freeze frame and live data with a scan tool; note crank/run behavior and any misfire counts for cylinder 6
Visual inspection of sensor, wiring harness, and connector for damage, oil, or corrosion
Backprobe sensor connector to verify reference voltage and ground
Measure signal voltage/waveform at the sensor while cranking and running (DVOM and oscilloscope preferred)
Wiggle test harness and connector while monitoring signal for intermittent faults
Check continuity and resistance between sensor connector and ECM pins for opens/shorts

Reference voltage: typically 5.0 V (±0.5 V) from the ECM (some systems may use another reference—verify OEM spec)
Signal output: variable waveform corresponding to combustion pressure; commonly within ~0.5–4.5 V under normal operation (manufacturer-dependent)
Quiescent/atmospheric signal: may show a low DC offset; during crank/run the waveform should vary with combustion events
Open circuit: no varying waveform or signal stuck at 0 V or reference rail
Short to battery: signal stuck near reference voltage (~5 V)
Short to ground: signal near 0 V with no waveform

Retrieve and record all related codes, freeze frame data, and live data for cylinder 6. Clear codes and attempt to re-create.
Perform a careful visual inspection of the sensor, connector, and harness routing near the cylinder head for damage, oil contamination, or loose connectors.
Backprobe the sensor connector. With ignition ON (engine off) verify the reference voltage and ground continuity to the ECM. Compare to OEM spec.
With a DVOM measure the signal voltage while cranking and idling. Use an oscilloscope if available to view waveform shape and timing relative to compression events.
Perform a wiggle test of the wiring and connector while monitoring the signal for intermittent changes. If signal changes, repair/replace wiring or connector.
Check continuity and resistance from the sensor connector to the ECM pin to identify opens/shorts. Repair any wiring faults and secure connectors.
If the wiring and connector test good but signal is invalid, replace the cylinder 6 pressure sensor and re-test.
If a new sensor does not clear the issue and wiring checks are good, inspect ECM connector pins for damage and consider ECM bench testing or replacement as a last resort.
If electrical diagnosis is complete and correct sensor behavior is confirmed but abnormal pressure traces persist, perform mechanical checks (compression, leak-down) on cylinder 6 to evaluate combustion issues.

Damaged/chafed wiring between the sensor and ECM causing intermittent or open circuit
Corroded or loose connector pins allowing poor signal or open circuit
Failed pressure sensor (internal short or no output)
Short to power or ground on the sensor signal or reference wire