P04E3: Crankcase Ventilation Hose Connection Sensor Circuit High

What it means

Same as P04E1 with the signal voltage above the plausible range. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.

At a glance

• Usually lights the check-engine light
• Affects emissions; the car can fail an emissions test

How it works

The crankcase ventilation hose connection sensor tells the control module whether the PCV hose is fitted at the engine. P04E3 sets when its signal rises above the plausible range, which can happen if the signal is shorted to a supply voltage or the circuit has a poor connection.

Common causes

Most likely first.

1. Signal shorted to supply
2. Connector pins corroded - high contact resistance
3. Supply wire pinched against B+ source

Symptoms

• Check engine light on
• Hose-connection status may be unavailable or incorrect
• Crankcase ventilation warning may appear

How to diagnose it

1. Check scan-tool data and freeze-frame information to confirm the hose connection signal is high when the fault occurs.
2. Verify the PCV hose is seated and inspect the sensor connector for corrosion, loose terminals, or pushed-back pins.
3. Inspect the signal and supply wiring for damage or pinching where a wire could contact a power source.
4. While monitoring the signal, gently move the connector and harness to check for a change in the high reading.
5. Test the signal circuit for a short to supply and test the sensor against the manufacturer's specification.

Common fixes

• Secure the sensor connector and clean corroded terminals as appropriate.
• Repair pinched or damaged wiring that is shorting the signal to supply.
• Repair loose or pushed-back connector terminals.
• Replace the hose connection sensor if the circuit is sound but its output remains above specification.

Can I keep driving?

If the PCV hose is secure and the vehicle runs normally, cautious driving is generally possible while arranging repair. Check that the hose stays connected, since an actual disconnection can affect running and emissions.