P0395
Cylinder 1 Pressure Sensor Circuit
Engine sensors
Generic OBD-II
High
What it means
P0395 indicates a fault in the cylinder 1 combustion-pressure sensor circuit. On engines that use in-cylinder pressure sensors for closed-loop combustion control, this feedback helps trim timing and fuelling — so a circuit fault usually makes the ECM fall back to a safe, reduced-power mode rather than stopping the engine. The cause is normally the sensor, its wiring, or the connector.
High
Can I keep driving? Often driveable but expect reduced power or limp mode — with cylinder-pressure feedback lost, the ECM runs a conservative fallback until it's fixed.
Common symptoms
What you'll notice
- Check-engine light on
- Reduced power or limp / fail-safe mode
- Rough idle or uneven running
- Possible increase in fuel use or emissions
Common causes
Most likely first
- Failed cylinder 1 combustion-pressure sensorLikely
- Signal wire open, shorted, or chafed in the circuitCommon
- Loose or corroded connector at the sensorCommon
- ECM fault (less likely — verify the sensor and wiring first)Less often
How to diagnose & fix
Work through it in order
- Scan and read freeze-frame data to confirm the fault is the cylinder 1 pressure-sensor circuit.
- Inspect the sensor connector and wiring for damage, heat, or corrosion.
- Back-probe the sensor for supply, ground, and a plausible signal against spec.
- Compare cylinder 1's reading to the other cylinders' pressure sensors if the engine has them.
- Replace the pressure sensor if it reads out of range with good wiring; consider the ECM last. Clear and re-test.
FAQ
Quick answers
Is it safe to drive with P0395?+
Short trips are usually possible, but the engine may run in reduced-power mode because the ECM has lost combustion feedback. Have it checked promptly.
Can I just clear P0395?+
It returns once the ECM re-tests the circuit. This is a sensor/wiring fault that needs repair, not just a reset.
Related codes
Often seen with P0395
Read & clear P0395 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX