P0400 on Mercedes-Benz
Exhaust Gas Recirculation (EGR) Flow Malfunction
P0400 on Mercedes-Benz vehicles indicates exhaust gas recirculation (egr) flow malfunction. Au7o has documented this code across 1 Mercedes-Benz model — most commonly on Sprinter. P0400 is a generic powertrain code indicating the engine computer detected a problem with exhaust gas recirculation (EGR) flow — either too much, too little, or incorrect flow compared to what was commanded. The EGR system routes a small amount of exhaust back into the intake to lower combustion temperatures and reduce emissions. A fault can cause rough idle, pinging/knock, increased emissions, and failed emissions testing, though it is generally not an immediate driving hazard. Typical repair costs on Mercedes-Benz range from $550 to $1,900, depending on the specific model and root cause.
Common Causes of P0400
- •Clogged or carbon-blocked EGR passages
- •Faulty EGR valve (stuck open or closed)
- •Faulty EGR position or DPFE/flow sensor
- •Vacuum or electrical control fault to the EGR valve
- •Blocked or cracked EGR tube
- •Wiring/connector issues
- •PCM fault (rare)
P0400 on Mercedes-Benz by Model
Mercedes-Benz Sprinter(1 issue)
- EGR Valve and EGR Cooler Carbon Clogging (Limp Mode, P0400-Series Codes)2007-2020
Sprinter diesels (OM642 V6 and OM651 4-cylinder) recirculate soot-laden exhaust through the EGR valve and cooler. Over tens of thousands of miles the valve and the cooler's small passages choke with hard carbon, causing the valve to stick, EGR flow to read out of range, rough running, power loss and limp mode. Short-trip/urban duty cycles accelerate the buildup. The cooler is often more clogged than the valve and frequently cannot be cleaned, requiring replacement.
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View P0400 across all makes →Frequently Asked Questions
What does P0400 mean on Mercedes-Benz?▼
P0400 stands for "Exhaust Gas Recirculation (EGR) Flow Malfunction." P0400 is a generic powertrain code indicating the engine computer detected a problem with exhaust gas recirculation (EGR) flow — either too much, too little, or incorrect flow compared to what was commanded. The EGR system routes a small amount of exhaust back into the intake to lower combustion temperatures and reduce emissions. A fault can cause rough idle, pinging/knock, increased emissions, and failed emissions testing, though it is generally not an immediate driving hazard. On Mercedes-Benz specifically, this code is documented across 1 model.
What causes P0400 on Mercedes-Benz vehicles?▼
Common causes on Mercedes-Benz: Clogged or carbon-blocked EGR passages, Faulty EGR valve (stuck open or closed), Faulty EGR position or DPFE/flow sensor, Vacuum or electrical control fault to the EGR valve, Blocked or cracked EGR tube. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0400 on a Mercedes-Benz?▼
Repair costs on Mercedes-Benz range from $550 to $1,900, depending on the specific model and root cause.
Which Mercedes-Benz models have P0400 documented?▼
Au7o has documented P0400 on 1 Mercedes-Benz model: Sprinter.