P0401 on Mitsubishi
Exhaust Gas Recirculation Flow Insufficient
P0401 on Mitsubishi vehicles indicates exhaust gas recirculation flow insufficient. Au7o has documented this code across 1 Mitsubishi model — most commonly on Outlander. 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.
Common Causes of P0401
- •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
P0401 on Mitsubishi by Model
Mitsubishi Outlander(1 issue)
- Engine Malfunction / 'Power Reduced' Warning from ECU Software (False P0401/P0404, TSB-22-13-001)2022
Early 2022 Outlanders with the 2.5L engine can illuminate the check-engine light and display an 'Engine malfunction / Power reduced — service now' message while idling or driving, often storing EGR-related codes (P0401/P0404) that do not reflect an actual hardware fault. Mitsubishi traced this to engine-ECU control software and issued TSB-22-13-001 to reflash the ECU with countermeasure software on vehicles built before December 16, 2021.
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View P0401 across all makes →Frequently Asked Questions
What does P0401 mean on 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 specifically, this code is documented across 1 model.
What causes P0401 on Mitsubishi vehicles?▼
Common causes on Mitsubishi: 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). Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0401 on a Mitsubishi?▼
Repair costs vary widely depending on the root cause and specific Mitsubishi model.
Which Mitsubishi models have P0401 documented?▼
Au7o has documented P0401 on 1 Mitsubishi model: Outlander.