P0399

Cylinder 1 Pressure Sensor Circuit Intermittent/Erratic

Severity

⚠️ Medium

Can you drive?

Limited driving only, diagnose soon

Approx. repair cost

$56–167 (est.)

Symptoms

Unstable engine operation
Misfires
Increased fuel consumption
Engine power drop
Check Engine Light Is On

Causes

Damage to the pressure sensor circuit
Poor contact in the sensor connector
Pressure sensor (CPS) fault
Short circuit in wiring harness
Problems with ECU software

How to Fix

Check the pressure sensor circuit for opens and short circuits
Inspect the sensor connector for oxidation or damage.
Test the pressure sensor using a multimeter or oscilloscope
Run ECU diagnostics for software updates
Replace the pressure sensor if it is faulty

Related codes

P0301 P0302 P0390 P0391