P0401
Exhaust Gas Recirculation (EGR) Flow Insufficient Detected
This means the system that recirculates exhaust gases back into the engine to reduce emissions isn't working properly, usually because it's clogged with carbon.
The Powertrain Control Module (PCM) has detected that the Exhaust Gas Recirculation (EGR) system is not flowing enough exhaust gas.
Common causes
- high
Clogged EGR valve or passages
Carbon buildup is the most common cause, restricting the flow of exhaust gas.
Typical part cost: $0-200 part/cleaning
- medium
Faulty EGR valve
The valve itself may be stuck closed or not opening sufficiently due to internal failure.
Typical part cost: $100-400 part
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First things to check
- 1Inspect EGR valve and passages for carbon buildup
- 2Test EGR valve operation (e.g., with a vacuum pump or scan tool)
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Related codes
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Frequently asked questions
Can I clean an EGR valve?
Yes, often an EGR valve can be removed and cleaned of carbon buildup using carburetor cleaner or a wire brush, which can resolve the P0401 code.
Does P0401 affect fuel economy?
A P0401 code itself might not directly cause a significant drop in fuel economy, but the underlying issue (like engine knocking) can indirectly lead to less efficient combustion.
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