OBD-II Code P0405 — What It Means & How to Fix It

What Does This Error Mean?

P0405 means the EGR (Exhaust Gas Recirculation) sensor A is sending a signal that is too low. The car's computer expected a higher voltage reading from this sensor. The EGR system reduces harmful emissions by recirculating exhaust gases back into the engine.

Affected Models

All OBD-II vehicles 1996+
Common in Ford F-150
Common in Chevrolet Silverado
Common in Dodge Ram
Common in Toyota Camry

Common Causes

Faulty EGR position sensor (most common cause)
Carbon buildup blocking the EGR valve
Damaged or corroded wiring to the EGR sensor
Vacuum leak in the EGR system
Failed EGR valve

How to Fix It

Use an OBD-II scanner to confirm P0405 and check for other codes.

Other EGR codes (P0400-P0404) appearing together help pinpoint whether the problem is the sensor, valve, or wiring.
Locate the EGR valve and sensor on your engine.

On most vehicles it is on the intake manifold. Check your owner's manual or search your specific make and model.
Inspect the wiring harness and connector on the EGR sensor.

Look for cracked insulation, corrosion, or loose pins. A bad connection is a common and cheap fix.
Clean the EGR valve and sensor port with EGR cleaner spray.

Carbon buildup can choke the valve and throw off sensor readings. This fix costs under $10 and takes 20 minutes.
Clear the code and take the car for a 20-minute drive.

If P0405 does not return, cleaning fixed it. If it returns within a day, the sensor or valve needs replacement.
Replace the EGR position sensor if the code returns.

The sensor is usually a plug-and-play part. Many DIYers replace it in under 30 minutes with basic tools.

When to Call a Professional

See a mechanic if the engine is misfiring, stalling, or running rough alongside this code. EGR sensor replacement typically costs $150-$350 including labor. Many drivers clear the code and monitor it — if it returns quickly, professional diagnosis is needed.

Frequently Asked Questions

Can I drive with a P0405 code?

Yes, in most cases it is safe to drive short distances. The car may use slightly more fuel and produce more emissions. Fix it soon to avoid failing an emissions test.

Will P0405 cause my car to fail emissions?

Yes — an active P0405 code will almost always trigger a failed emissions test. The check engine light alone is a fail in most states. Clear the code after fixing and drive for a complete readiness cycle before testing.

How much does it cost to fix P0405?

If cleaning fixes it, the cost is under $10 for a can of EGR cleaner. A new EGR sensor runs $50-$150 for the part. Full EGR valve replacement with labor typically costs $200-$400.