Mercedes-Benz Diagnostic Trouble Codes
Common OBD2 fault codes found on Mercedes-Benz vehicles with model-specific causes, known issues, TSBs, and adjusted repair cost estimates. Each guide is tailored for Mercedes-Benz owners.
Ignition
Crankshaft Position - Camshaft Position Correlation (Bank 1 Sensor B)
Mercedes E-Class • 2005–2024
The M276 V6 and M278 V8 use camshaft adjusters that are a known weak point. Mercedes calls these sol...
Crankshaft Position - Camshaft Position Correlation (Bank 2 Sensor A)
Mercedes E-Class • 2005–2024
The M276 V6 and M278 V8 both commonly set P0018 around 100,000 to 150,000 km. Mercedes camshaft adju...
Crankshaft Position - Camshaft Position Correlation (Bank 2 Sensor B)
Mercedes E-Class • 2005–2024
The M276 V6 in the W212 and W213 E-Class commonly sets P0019 due to camshaft adjuster magnet failure...
Camshaft Position Sensor "A" Circuit Low Input (Bank 1 or Single Sensor)
Mercedes C-Class • 2007-2024
W204 with the M271 four-cylinder is well known for camshaft sensor failures. The wiring loom is inte...
Camshaft Position Sensor "A" Circuit High Input (Bank 1 or Single Sensor)
Mercedes C-Class • 2007-2024
M271 in the W204 C-Class is documented for cam sensor failures producing P0343 alongside related cam...
Emissions
"A" Camshaft Position - Timing Over-Advanced or System Performance (Bank 2)
Mercedes E-Class • 2005–2024
The M276 V6 sets P0021 frequently due to bank 2 camshaft adjuster magnet failure. Mercedes adjusters...
"A" Camshaft Position - Timing Retarded (Bank 2)
Mercedes E-Class • 2005–2024
The M276 V6 sets P0022 frequently due to bank 2 camshaft adjuster magnet failure or sticking. Merced...
O2 Sensor Circuit Malfunction (Bank 1, Sensor 2)
Mercedes C-Class • 2007–2024
The W204 M271 1.8L Kompressor commonly throws P0136 around 100,000–130,000 km from standard sensor a...
O2 Sensor Circuit Low Voltage (Bank 1, Sensor 2)
Mercedes C-Class • 2007–2024
The W204 M271 1.8L Kompressor frequently triggers P0137 around 100,000–130,000 km from standard sens...
O2 Sensor Circuit High Voltage (Bank 1, Sensor 2)
Mercedes C-Class • 2007–2024
The W204 M271 1.8L Kompressor can throw P0138 from injector seal weeping around 130,000+ km. The W20...
O2 Sensor Circuit Slow Response (Bank 1, Sensor 2)
Mercedes C-Class • 2007–2024
The W204 M271 1.8L Kompressor reliably triggers P0139 around 130,000–150,000 km from normal sensor a...
O2 Sensor Circuit No Activity Detected (Bank 1, Sensor 2)
Mercedes C-Class • 2007–2024
The W204 M271 1.8L Kompressor commonly triggers P0140 from heater element burnout around 130,000–150...
O2 Sensor Circuit Low Voltage (Bank 1, Sensor 3)
Mercedes Sprinter • 2010–2024
The Sprinter OM651 and OM642 diesel both run a Sensor 3 position downstream of the SCR catalyst. P01...
O2 Sensor Circuit High Voltage (Bank 1, Sensor 3)
Mercedes Sprinter • 2010–2024
The Sprinter OM651 and OM642 diesel both have a known P0144 pattern past 200,000 km, driven by AdBlu...
O2 Sensor Circuit Slow Response (Bank 1, Sensor 3)
Mercedes Sprinter • 2010–2024
The Sprinter OM651 and OM642 diesel commonly trigger P0145 past 200,000 km from sensor element aging...
O2 Sensor Circuit No Activity Detected (Bank 1, Sensor 3)
Mercedes Sprinter • 2010–2024
The Sprinter OM651 and OM642 diesel triggers P0146 around 200,000+ km from a combination of heater b...
O2 Sensor Heater Circuit Malfunction (Bank 1, Sensor 3)
Mercedes Sprinter • 2010–2024
The Sprinter OM651 and OM642 diesel triggers P0147 most often around 200,000+ km from standard heate...
Exhaust Gas Recirculation Flow Excessive Detected
Mercedes Sprinter • 2010–2024
Sprinter vans with the OM651 2.1 CDI engine are heavy commercial users that see EGR faults early due...
Exhaust Gas Recirculation Control Circuit Malfunction
Mercedes Sprinter • 2010–2024
OM651 Sprinters develop P0403 when the EGR solenoid winding fails from continuous duty cycles in com...
Exhaust Gas Recirculation Control Circuit Range/Performance
Mercedes Sprinter • 2010–2024
OM651 Sprinters often see P0404 alongside P0401 due to heavy commercial duty cycles. The position se...
Exhaust Gas Recirculation Sensor "A" Circuit Low
Mercedes Sprinter • 2010–2024
OM651 Sprinter EGR position sensors fail regularly under heavy commercial use, often before 120,000 ...
Exhaust Gas Recirculation Sensor "A" Circuit High
Mercedes Sprinter • 2010–2024
OM651 Sprinter EGR sensor open-circuit failures are less common than shorts (P0405), but when they a...
Exhaust Gas Recirculation Sensor "B" Circuit Low
Mercedes Sprinter • 2014–2024
OM642 V6 diesel Sprinters (3.0 CDI) use dual EGR valves with dual sensors. P0407 indicates the bank-...
Exhaust Gas Recirculation Sensor "B" Circuit High
Mercedes Sprinter • 2014–2024
OM642 V6 Sprinters (3.0 CDI) develop P0408 when the bank-2 EGR position sensor fails open. The bank-...
Warm Up Catalyst Efficiency Below Threshold (Bank 1)
Mercedes-Benz E-Class • 2009-2024
On the W212 and W213 E-Class with the M276 V6 or M278 V8, P0421 typically appears alongside lean cod...
Main Catalyst Efficiency Below Threshold (Bank 1)
Mercedes-Benz E-Class • 2009-2024
On W212 and W213 E-Class with M276 V6 or M278 V8, P0422 commonly appears at 180,000 km. The Bank 1 m...
Heated Catalyst Efficiency Below Threshold (Bank 1)
Mercedes-Benz E-Class • 2019-2024
On the W213 facelift E-Class with M256 inline-6 and M264 four-cylinder mild-hybrid powertrains, P042...
Heated Catalyst Temperature Below Threshold (Bank 1)
Mercedes-Benz E-Class • 2019-2024
On the W213 facelift E-Class with M256 inline-6 and M264 four-cylinder mild-hybrid platforms, P0424 ...
Catalyst System Efficiency Below Threshold (Bank 2)
Mercedes-Benz C-Class • 2005-2024
P0430 shows up on the V6 and V8 C-Class models (C280, C300, C350, C43, C63). The V6 layout places th...
Warm Up Catalyst Efficiency Below Threshold (Bank 2)
Mercedes-Benz E-Class • 2009-2024
On W212 and W213 E-Class with the M276 V6 or M278 V8, P0431 typically appears alongside Bank 2 lean ...
Main Catalyst Efficiency Below Threshold (Bank 2)
Mercedes-Benz E-Class • 2009-2024
On W212 and W213 E-Class with M276 V6 or M278 V8 engines, P0432 commonly appears at 180,000 km on th...
Heated Catalyst Efficiency Below Threshold (Bank 2)
Mercedes-Benz E-Class • 2019-2024
On the W213 facelift E-Class with M256 inline-6 mild-hybrid and M177 V8 (E63), Bank 2 carries its ow...
Heated Catalyst Temperature Below Threshold (Bank 2)
Mercedes-Benz E-Class • 2019-2024
On the W213 facelift E-Class with M256 inline-6 mild-hybrid and M177 V8 (E63), P0434 typically point...
Diesel Particulate Filter Differential Pressure Too Low (Bank 1)
Mercedes-Benz Sprinter • 2010-2024
The Sprinter OM651 and OM642 engines develop P244A from soot accumulation in the pressure sensing tu...
Diesel Particulate Filter Differential Pressure Too High (Bank 1)
Mercedes-Benz Sprinter • 2010-2024
Sprinter OM651 and OM642 DPFs clog faster than passenger-car filters because the duty cycle is heavy...
DEF (AdBlue) System: Time Limit For Restricted Operation Mode Exceeded
Mercedes-Benz Sprinter • 2014-2024
Sprinter OM642 and OM651 with Euro 6 emissions use BlueTEC SCR. Mercedes implements the strictest co...
Fuel System
Fuel Trim Malfunction (Bank 1)
Mercedes C-Class • 2007-2024
The M271 and M274 engines can develop intake manifold swirl flap issues that cause vacuum leaks and ...
Fuel Trim Malfunction (Bank 2)
Mercedes E-Class • 2011-2024
W212 E-Class with the M276 V6 commonly logs P0173 from an air leak at the Bank 2 intake manifold run...
System Too Lean (Bank 2)
Mercedes-Benz C-Class • 2005-2024
Four-cylinder C-Class models are single-bank and report P0171; the V6 and V8 variants (M272, M273, M...
System Too Rich (Bank 2)
Mercedes E-Class • 2011-2024
W212 E-Class with the M276 V6 logs P0175 most often from a stuck-open Bank 2 injector at high mileag...
Fuel Rail Pressure Sensor Circuit Range/Performance
Mercedes C-Class • 2008-2024
The M274 2.0T and OM651 diesel engines use Bosch fuel rail pressure sensors. On the diesel, P0191 ca...
Injector Circuit / Open - Cylinder 1
Mercedes C-Class • 2007-2024
On OM651 and other CDI diesels the common-rail injectors are expensive and each carries a calibratio...
Injector Circuit / Open - Cylinder 2
Mercedes C-Class • 2007-2024
On OM651 and other CDI diesels the common-rail injectors are expensive and each carries a calibratio...
Injector Circuit / Open - Cylinder 3
Mercedes C-Class • 2007-2024
On OM651 and other CDI diesels the common-rail injectors are expensive and each carries a calibratio...
Injector Circuit / Open - Cylinder 4
Mercedes C-Class • 2007-2024
On OM651 and other CDI diesels the common-rail injectors are expensive and each carries a calibratio...
Injector Circuit / Open - Cylinder 5
Mercedes C-Class • 2007-2024
Inline-6 petrol (M256) and inline-6 diesel (OM656) C-Class variants have a cylinder 5. The OM656 and...
Injector Circuit / Open - Cylinder 6
Mercedes C-Class • 2007-2024
Inline-6 petrol (M256), V6 petrol (M276), and inline-6 diesel (OM656) C-Class variants have a cylind...
Misfire
Cylinder 4 Misfire Detected
Mercedes C-Class • 2007-2024
The M274 2.0-litre turbo engine in the C200/C250 (W205) has documented issues with ignition coil fai...
Cylinder 6 Misfire Detected
Mercedes C-Class • 2008-2018
W204 C350 with the M272 V6 commonly logs P0306 from a worn cylinder 6 ignition coil and a small vacu...
Electrical
Glow Plug / Heater Circuit "A" Malfunction
Mercedes-Benz (OM651 diesel) • 2008-2018
The OM651 four-cylinder diesel uses a glow plug control module that the ECU monitors for circuit fau...
Brake Switch "A"/"B" Correlation
Mercedes C-Class • 2008-2024
W204 and W205 C-Class have well-documented brake switch failures, often setting P0504 together with ...
ECM/PCM Processor Fault
Mercedes C-Class • 2007-2024
W204 and W205 C-Class models with ME9.7 and MED40 ECUs commonly develop P0606 from moisture intrusio...
Glow Plug Control Module Circuit
Mercedes-Benz (OM651 diesel) • 2008-2018
The OM651 uses a glow plug control module the ECU monitors for circuit integrity. P0670 here is comm...
Cylinder 1 Glow Plug Circuit
Mercedes-Benz (OM651 diesel) • 2008-2018
The OM651 control module monitors each plug and reports per-cylinder faults, so P0671 points at cyli...
Cylinder 2 Glow Plug Circuit
Mercedes-Benz (OM651 diesel) • 2008-2018
The OM651 control module monitors each plug and reports per-cylinder faults, so P0672 points at cyli...
Cylinder 3 Glow Plug Circuit
Mercedes-Benz (OM651 diesel) • 2008-2018
The OM651 control module monitors each plug and reports per-cylinder faults, so P0673 points at cyli...
Cylinder 4 Glow Plug Circuit
Mercedes-Benz (OM651 diesel) • 2008-2018
The OM651 control module monitors each plug and reports per-cylinder faults, so P0674 points at cyli...
Transmission
Transmission Control System Malfunction
Mercedes C-Class • 2007-2024
The W204 C-Class with the 722.9 (7G-Tronic) transmission commonly triggers P0700 due to conductor pl...
Output Speed Sensor Circuit Malfunction
Mercedes C-Class • 2007-2024
The W204 and W205 C-Class with the 722.9 (7G-Tronic) transmission uses a speed sensor integrated int...
Torque Converter Clutch Circuit Performance/Stuck Off
Mercedes C-Class • 2007-2024
The W204 C-Class with the 722.9 (7G-Tronic) transmission is known for TCC shudder and lockup issues....
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