P0401: EGR Insufficient Flow — Guide
Key Takeaway
P0401 = EGR valve not flowing enough exhaust gas. It's usually carbon buildup.
What Is the EGR System?
The Exhaust Gas Recirculation (EGR) system sends a small amount of exhaust back into the intake to reduce combustion temperatures and lower NOx emissions.
Common P0401 Causes
| Cause | Likelihood | Fix Cost |
|---|---|---|
| Carbon buildup in EGR valve | Very common | $50 (clean) – $300 (replace) |
| Clogged EGR passages | Common | $100 – $300 (clean passages) |
| Failed EGR valve | Moderate | $200 – $500 |
| EGR position sensor | Less common | $100 – $200 |
| Vacuum line disconnected (vacuum EGR) | Less common | $0 – $20 |
Can You Drive With P0401?
Yes. P0401 is a low-severity emissions code. The engine may run slightly hotter under load and you'll fail emissions, but it's safe to drive.
ProHow Steer Helps
Steer identifies P0401, rates it as low severity, and recommends starting with cleaning before replacement.
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