P0401 on Saturn
Exhaust Gas Recirculation Flow Insufficient
P0401 on Saturn vehicles indicates exhaust gas recirculation flow insufficient. Au7o has documented this code across 1 Saturn model — most commonly on S-Series. 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 Saturn range from $20 to $250, 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 Saturn by Model
Saturn S-Series(1 issue)
- EGR Valve Clogging Causing P0401/P0404/P1404 Codes1996-1999
Beginning with OBD-II in 1996, the Saturn S-Series 1.9L EGR system is highly susceptible to carbon clogging. The narrow gap between the EGR pintle and its passage is easily fouled by exhaust carbon, especially on engines that burn oil (a chronic issue on this engine — see the oil consumption issue). The most common codes are P0401 (insufficient EGR flow), P0404 (EGR control circuit range/performance), and the Saturn-specific P1404 (EGR closed position). Replacing the valve alone rarely fixes the problem because the EGR passages in the cylinder head and intake manifold are also clogged. The condition worsens markedly once oil consumption begins.
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View P0401 across all makes →Frequently Asked Questions
What does P0401 mean on Saturn?▼
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 Saturn specifically, this code is documented across 1 model.
What causes P0401 on Saturn vehicles?▼
Common causes on Saturn: 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 Saturn?▼
Repair costs on Saturn range from $20 to $250, depending on the specific model and root cause.
Which Saturn models have P0401 documented?▼
Au7o has documented P0401 on 1 Saturn model: S-Series.