P0401 on Citroen
Exhaust Gas Recirculation Flow Insufficient
P0401 on Citroen vehicles indicates exhaust gas recirculation flow insufficient. Au7o has documented this code across 1 Citroen model — most commonly on C4. 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. Typical repair costs on Citroen range from $150 to $500, depending on the specific model and root cause.
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 Citroen by Model
Citroen C4(1 issue)
- EGR Valve Carbon Buildup2004-2021
The C4 diesel EGR valve accumulates carbon deposits that cause it to stick open or closed. The blocked EGR increases exhaust emissions, causes rough idle, and can trigger the engine management warning light.
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View P0401 across all makes →Frequently Asked Questions
What does P0401 mean on Citroen?▼
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 Citroen specifically, this code is documented across 1 model.
What causes P0401 on Citroen vehicles?▼
Common causes on Citroen: 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 Citroen?▼
Repair costs on Citroen range from $150 to $500, depending on the specific model and root cause.
Which Citroen models have P0401 documented?▼
Au7o has documented P0401 on 1 Citroen model: C4.