Code
P2348
Generic
P — Powertrain
Cylinder 9 Pressure Sensor Circuit
AI status
Completed
Completed
100%
Causes
- Open, shorted, or damaged wiring to the cylinder 9 pressure sensor
- Corroded, loose, or pushed-out connector pins at the sensor or harness
- Failed/faulty cylinder 9 pressure sensor
- Low or missing reference voltage or ground to the sensor
- Water ingress or contamination at the sensor connector
- Faulty ECM input or internal circuit failure
Symptoms
- Malfunction Indicator Lamp (MIL) or check engine light ON
- Rough idle or cylinder-specific misfire (depending on engine strategy)
- Reduced engine power or drivability issues
- Poor fuel economy
- Possible hard start or no-start (rare, depending on system)
What to check
- Read and record freeze frame and stored/ pending codes with a scan tool
- Visually inspect sensor, connector, and wiring for damage, corrosion, or fluid intrusion
- Check connector pins for bent, pushed-out, or corroded terminals
- Verify battery voltage and ground integrity at the sensor circuit
- Backprobe sensor signal, reference, and ground with a multimeter/oscilloscope
- Wiggle test wiring while monitoring live sensor values for intermittent faults
Signal parameters
- Reference supply: typically 5 V (verify factory spec)
- Signal output: commonly analog 0.5–4.5 V proportional to pressure (verify with manufacturer data)
- Ground: low-resistance connection to chassis/engine ground
- Open circuit: OL or >10 kΩ between signal pin and ECM
- Short to ground: signal ~0 V
- Short to battery: signal ~battery voltage (~12 V)
Diagnostic algorithm
- Use a scan tool to confirm P2348 and note any related codes or freeze-frame data.
- Visually inspect cylinder 9 pressure sensor and harness for damage, tears, or contamination. Repair obvious damage.
- Disconnect connector and inspect pins for corrosion, bending, or pushed-out terminals; clean or repair as needed.
- With ignition ON (engine off), measure reference voltage at the sensor connector; confirm proper supply per spec.
- Measure sensor ground for good continuity to chassis/engine ground (low ohms).
- Backprobe the signal wire with a multimeter/oscilloscope while cranking/running; verify signal amplitude and behavior matches expected pressure-dependent output.
- Perform a wiggle test of harness and connector while monitoring live data to reveal intermittent faults.
- If available and applicable, swap the cylinder 9 sensor with a known-good same-type sensor from another cylinder to see if the code follows the sensor.
- Check continuity and resistance of signal wire from sensor connector to ECM pin to identify opens/shorts (refer to wiring diagram for pin locations).
- Repair or replace damaged wiring, connector, or sensor. If wiring repair is performed, protect and secure harness to prevent future chafe.
- After repair, clear codes, perform a functional test/drive cycle and monitor for reappearance of the code.
- If fault persists after harness and sensor replacement, consider ECM input testing or replacement per factory diagnostics.
Likely causes
- Wiring harness chafe or connector corrosion causing intermittent connection
- Failed sensor (no output or out-of-range voltage)
- Broken or shorted signal wire to ECM
- Loose or missing sensor ground or reference supply
- ECM fault (less common)
Fault status
Status
P2348 - Cylinder 9 Pressure Sensor Circuit: circuit malfunction detected (open/short/intermittent/out-of-range signal).
Repair difficulty: Medium
Diagnostic time: 1-3 hours
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