P0203 on Mercedes-Benz
Injector Circuit/Open - Cylinder 3
P0203 on Mercedes-Benz vehicles indicates injector circuit/open - cylinder 3. Au7o has documented this code across 2 Mercedes-Benz models — most commonly on GLK-Class, Sprinter. This code means the Engine Control Module detected an electrical problem (open circuit or out-of-range resistance) in the fuel injector control circuit for cylinder 3. The ECM pulses each injector electrically and watches the circuit to verify it is operating. P0203 means the expected feedback for cylinder 3's injector is missing or abnormal, so that cylinder may not be fueling properly. The typical result is a misfire, rough idle, and reduced performance traceable to cylinder 3. Typical repair costs on Mercedes-Benz range from $300 to $3,000, depending on the specific model and root cause.
Common Causes of P0203
- •Damaged or corroded injector connector at cylinder 3
- •Open or shorted wiring in the injector control circuit
- •Failed (electrically open) fuel injector on cylinder 3
- •Loose or backed-out connector pin
- •Poor ground or power feed to the injector
- •Faulty injector driver inside the ECM/PCM
- •Chafed harness causing intermittent open
P0203 on Mercedes-Benz by Model
Mercedes-Benz GLK-Class(1 issue)
- Diesel Injector Leak and Black Death (OM651)2010-2015
The OM651 diesel injectors in the GLK develop a condition known as "Black Death" where the copper injector sealing washers fail, allowing combustion gases to escape around the injector. The escaping gases carbonize and create hard black tar deposits around the injector bore, eventually welding the injector in place and making removal extremely difficult.
Mercedes-Benz Sprinter(1 issue)
- Diesel Injector Failure and Black Death (OM651/OM654)2010-2025
Sprinter diesel injectors develop seal failures leading to the "Black Death" condition where combustion gases leak past the injector copper washers, carbonizing and creating hard tar deposits around the injector bore. This is the most common and feared Sprinter repair, as advanced cases require expensive injector extraction procedures when the carbon welds the injectors in place.
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View P0203 across all makes →Frequently Asked Questions
What does P0203 mean on Mercedes-Benz?▼
P0203 stands for "Injector Circuit/Open - Cylinder 3." This code means the Engine Control Module detected an electrical problem (open circuit or out-of-range resistance) in the fuel injector control circuit for cylinder 3. The ECM pulses each injector electrically and watches the circuit to verify it is operating. P0203 means the expected feedback for cylinder 3's injector is missing or abnormal, so that cylinder may not be fueling properly. The typical result is a misfire, rough idle, and reduced performance traceable to cylinder 3. On Mercedes-Benz specifically, this code is documented across 2 models.
What causes P0203 on Mercedes-Benz vehicles?▼
Common causes on Mercedes-Benz: Damaged or corroded injector connector at cylinder 3, Open or shorted wiring in the injector control circuit, Failed (electrically open) fuel injector on cylinder 3, Loose or backed-out connector pin, Poor ground or power feed to the injector. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0203 on a Mercedes-Benz?▼
Repair costs on Mercedes-Benz range from $300 to $3,000, depending on the specific model and root cause.
Which Mercedes-Benz models have P0203 documented?▼
Au7o has documented P0203 on 2 Mercedes-Benz models: GLK-Class, Sprinter.