What it means
A dedicated sensor monitors whether the PCV hose is fitted to its connector at the engine. The ECU detects a circuit fault on this sensor - cannot determine whether the hose is connected. Required by some emissions regulations to flag a disconnected PCV hose immediately.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
A crankcase ventilation hose connection sensor tells the control module whether the PCV hose is fitted at its engine connection. P04E1 sets when the sensor circuit has an electrical fault and the module cannot reliably determine the hose connection status.
Common causes
Most likely first.
- Open or short in hose-connection sensor wiring
- Loose or corroded connector
- Failed hose-connection sensor
Symptoms
- Check engine light on
- Hose-connection status may be unavailable or incorrect
- Crankcase ventilation warning may appear
How to diagnose it
- Check freeze-frame data and scan-tool status for the crankcase ventilation hose connection to see whether the reading is missing or implausible.
- Visually confirm the PCV hose is seated at the engine connection and inspect it for cracks, disconnection, or damage.
- Inspect the hose connection sensor and its connector for looseness, corrosion, damaged pins, or moisture.
- Check the sensor wiring for breaks, chafing, or contact with hot or moving parts.
- Test the sensor circuit and sensor operation against the manufacturer's specification to identify an open, short, or failed sensor.
Common fixes
- Reconnect or replace a damaged PCV hose.
- Secure the sensor connector and clean corroded terminals as appropriate.
- Repair an open, shorted, or chafed section of sensor wiring.
- Replace the hose connection sensor if its circuit and wiring are sound but it fails its specified test.
Can I keep driving?
If the PCV hose is securely connected and the engine runs normally, cautious driving is generally possible while arranging repair. If the hose is loose or disconnected, refit it promptly because unmetered air and crankcase vapours can affect running and emissions.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.