P0401 on Mitsubishi: How to Diagnose & Fix
Exhaust Gas Recirculation Flow Insufficient
1 Mitsubishi model · 1 documented issue
P0401 on Mitsubishi by model: symptoms, diagnosis and fix
Mitsubishi TSB-22-13-001 covers 2022 Outlander vehicles built before December 16, 2021. The check-engine light or an Engine Malfunction / Power Reduced Service Now warning may appear while idling or driving, with P0401, P0404 or other codes, because the engine ECU requires countermeasure software. The bulletin directs technicians to save and erase codes, diagnose hard codes that will not clear, perform the reflash first for the applicable population and diagnose further only if codes persist.
Common Symptoms
- 2022 VIN and pre-December 16, 2021 build date verified
- ALL-DTC result and software level captured
- warning and codes rechecked after applicable ECU reflash
How to Fix
Verify the VIN, build date, ECU software level and stored codes against TSB-22-13-001. Preserve the ALL-DTC result and diagnose any applicable hard code that will not clear, then have a qualified Mitsubishi technician reprogram the engine ECU with the specified countermeasure software and confirm operation. Do not buy an EGR valve, sensor, wiring harness or ECU from this page; persistent codes after the applicable reflash require their own documented diagnosis.
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Sources for this issue (2)
P0401 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0401 mean on a Mitsubishi?
P0401 stands for "Exhaust Gas Recirculation Flow Insufficient." This code means the Exhaust Gas Recirculation (EGR) system is not flowing enough exhaust back into the engine. The EGR system recirculates a small amount of exhaust into the intake to lower combustion temperatures and reduce nitrogen oxide (NOx) emissions; the computer has determined the actual flow is below what it commanded. The most common reason is carbon buildup clogging the EGR valve or its passages. You may notice pinging/knocking, rough idle, or a check engine light, and the car will fail emissions testing. On Mitsubishi it is documented across 1 model: Outlander.
What are the most common causes of P0401?
The most common causes of P0401 are: Carbon buildup clogging the EGR valve or passages, Stuck or faulty EGR valve, Blocked or restricted EGR ports/tubes, Faulty EGR temperature or position sensor, Faulty DPFE/EGR pressure sensor (on applicable systems), Vacuum leak or failed vacuum control (vacuum-operated EGR), Wiring or connector problems at the EGR valve. The specific cause varies by vehicle.
How much does it cost to fix P0401 on a Mitsubishi?
Repair costs vary widely with the root cause and Mitsubishi model; each issue on this page carries its own estimate where one is published.
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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.