P0401: Exhaust Gas Recirculation Flow Insufficient Detected
Short answer: P0401 means “Exhaust Gas Recirculation Flow Insufficient Detected”. It is a standard OBD-II code, so the basic meaning is the same on every car. Below is what it means on each of the 6 cars we cover, with a link to the full page for each car.
Standard OBD-II code Same meaning on all cars (SAE J2012).
P0401 on each car
| Car | Meaning on this car | Confidence |
|---|---|---|
| Toyota Passo (1st gen) | Stepper Motor Type Egr Valve System Malfunction (Func (P0401/79) | high |
| Toyota Corolla (11th gen, E170) | Exhaust Gas Recirculation Flow Insufficient Detected | medium |
| Toyota Corolla (10th gen, E140) | Exhaust Gas Recirculation Flow Insufficient Detected | medium |
| Honda City (5th gen, GM2) | Exhaust Gas Recirculation Flow Insufficient Detected | medium |
| Honda Civic (10th gen, FC) | Exhaust Gas Recirculation Flow Insufficient Detected | medium |
| Suzuki Wagon R (Pakistan, K10B) | Exhaust Gas Recirculation Flow Insufficient Detected | medium |
Symptoms
- Check engine light on
Likely causes
- The DPFE (differential pressure feedback EGR) sensor is faulty and needs
- To be replaced
- There is a blockage in the EGR (tube), most likely carbon buildup
- The EGR valve is faulty
- The EGR valve may not be opening due to a lack of vaccuum
What to check, in order
- Read the code and live data with an OBD-II scanner
- Look for exhaust or vacuum leaks and check the wiring of the sensor or valve
- Test the part before replacing it
- Fix the cause, clear the code and test-drive
Causes and checks above are the general meaning. The exact test steps and values differ by car: open your car’s page.