Mercedes-Benz Diagnostic Trouble Codes

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...

"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

On the W204 C-Class with the M271 1.8 Kompressor petrol, P0136 is commonly the downstream sensor or ...

O2 Sensor Circuit Low Voltage (Bank 1, Sensor 2)

Mercedes C-Class • 2007-2024

On the W204 C-Class with the M271 1.8 Kompressor petrol, P0137 is commonly the downstream sensor age...

O2 Sensor Circuit High Voltage (Bank 1, Sensor 2)

Mercedes C-Class • 2007-2024

On the W204 C-Class with the M271 1.8 Kompressor petrol, P0138 is either a genuine rich condition (c...

O2 Sensor Circuit Slow Response (Bank 1, Sensor 2)

Mercedes C-Class • 2007-2024

On the W204 C-Class with the M271 1.8 Kompressor petrol, P0139 is typically the downstream sensor ag...

O2 Sensor Circuit No Activity Detected (Bank 1, Sensor 2)

Mercedes C-Class • 2007-2024

On the W204 C-Class with the M271 1.8 Kompressor petrol, P0140 commonly comes from heater element bu...

O2 Sensor Circuit Malfunction (Bank 2, Sensor 1)

Mercedes-Benz C-Class (V6) • 2005-2011

On Mercedes V6 and V8 engines, including the M272 V6 in the C 230, C 280, C 300 and C 350, bank 1 is...

O2 Sensor Circuit Low Voltage (Bank 2, Sensor 1)

Mercedes-Benz C-Class (V6) • 2005-2011

On Mercedes V6 and V8 engines, including the M272 V6 in the C 230, C 280, C 300 and C 350, bank 1 is...

O2 Sensor Circuit High Voltage (Bank 2, Sensor 1)

Mercedes-Benz C-Class (V6) • 2005-2011

On Mercedes V6 and V8 engines, including the M272 V6 in the C 230, C 280, C 300 and C 350, bank 1 is...

O2 Sensor Circuit Slow Response (Bank 2, Sensor 1)

Mercedes-Benz C-Class (V6) • 2005-2011

On Mercedes V6 and V8 engines, including the M272 V6 in the C 230, C 280, C 300 and C 350, bank 1 is...

O2 Sensor Circuit No Activity Detected (Bank 2, Sensor 1)

Mercedes-Benz C-Class (V6) • 2005-2011

On Mercedes V6 and V8 engines, including the M272 V6 in the C 230, C 280, C 300 and C 350, bank 1 is...

O2 Sensor Heater Circuit Malfunction (Bank 2, Sensor 1)

Mercedes-Benz C-Class (V6) • 2005-2011

On Mercedes V6 and V8 engines, including the M272 V6 in the C 230, C 280, C 300 and C 350, bank 1 is...

O2 Sensor Circuit Malfunction (Bank 2, Sensor 2)

Mercedes-Benz E-Class • 2005-2011

The M272 V6 used in the W211 and early W212 E-Class (E 230 to E 350) has four oxygen sensors, one be...

O2 Sensor Circuit Low Voltage (Bank 2, Sensor 2)

Mercedes-Benz E-Class • 2005-2011

On the M272 V6 the bank 2 downstream sensor is on the left-hand exhaust, viewed in the direction of ...

O2 Sensor Circuit High Voltage (Bank 2, Sensor 2)

Mercedes-Benz E-Class • 2005-2011

With separate sensors and fuel trims per bank, an M272 V6 that runs rich only on the left-hand bank ...

O2 Sensor Circuit Slow Response (Bank 2, Sensor 2)

Mercedes-Benz E-Class • 2005-2011

The M272 V6 has a downstream sensor on each bank, so compare the two in live data: if only the left-...

O2 Sensor Circuit No Activity Detected (Bank 2, Sensor 2)

Mercedes-Benz E-Class • 2005-2011

Bank 2 on the M272 V6 is the left-hand bank viewed in the direction of travel, so start at the conne...

O2 Sensor Heater Circuit Malfunction (Bank 2, Sensor 2)

Mercedes-Benz E-Class • 2005-2011

The M272 V6 has four heated oxygen sensors, and P0161 points to the heater of the post-catalyst sens...

Exhaust Gas Recirculation Flow Excessive Detected

Mercedes Sprinter • 2010-2024

Sprinter vans with the OM651 2.1 CDI engine see heavy commercial use and a lot of low-load city driv...

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

On OM651 Sprinters an open circuit in the EGR sensor wiring is often traced to road salt reaching th...

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 points to the Bank 1 pre-cat close t...

Main Catalyst Efficiency Below Threshold (Bank 1)

Mercedes-Benz E-Class • 2009-2024

On W212 and W213 E-Class with the M272 or M276 V6 or the M278 V8, P0422 points to the Bank 1 main ca...

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 the M276 V6 or the M278 V8 (E500/E550), P0432 points to the Bank 2 mai...

Heated Catalyst Temperature Below Threshold (Bank 2)

Mercedes-Benz E-Class • 2019-2024

On the W213 facelift E-Class, only the M177 V8 in the E63 is a two-bank engine and can set a genuine...

Diesel Particulate Filter Differential Pressure Too Low (Bank 1)

Mercedes-Benz Sprinter • 2010-2024

The Sprinter OM651 and OM642 engines can develop P244A from soot accumulation in the pressure sensin...

Diesel Particulate Filter Differential Pressure Too High (Bank 1)

Mercedes-Benz Sprinter • 2010-2024

Sprinter OM651 and OM642 filters load up faster on vans doing stop-start delivery work, because the ...

Particulate Matter Sensor Temperature Circuit

Mercedes-Benz C-Class diesel • 2018-2021

Diesel C-Class models of this generation use a soot particulate sensor in the exhaust after the part...

Particulate Matter Sensor Temperature Circuit

Mercedes-Benz GLC 220d / 250d • 2017-2020

The diesel GLC uses the same soot particulate sensor as the C-Class. It is reached from underneath b...

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

On the W212 E-Class with the M276 V6, check the Bank 2 upstream lambda sensor and look for air leaks...

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, M276 an...

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

V6 petrol (M276) and V6 diesel (OM642) C-Class variants have a cylinder 5. The OM642 diesel uses cos...

Injector Circuit / Open - Cylinder 6

Mercedes C-Class • 2007-2024

V6 petrol (M276) and V6 diesel (OM642) C-Class variants have a cylinder 6. The OM642 diesel uses cos...

Engine Oil Temperature Sensor

Mercedes-Benz C-Class • 2005-2024

Mercedes also takes oil temperature from a combined sensor in the sump that reports level, temperatu...

Engine Oil Temperature Sensor Range/Performance

Mercedes-Benz C-Class • 2005-2024

Mercedes fits a combined oil level sensor in the oil pan that reports oil level, oil temperature and...

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...

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 can log P0306 from a worn cylinder 6 ignition coil or spark plug. Cylinde...

Cylinder 7 Misfire Detected

Mercedes-Benz S500 / S550 (W221, M273 V8) • 2005-2011

The M273 V8 is port-injected, so the intake-valve carbon that troubles direct-injection V8s is not t...

Cylinder 8 Misfire Detected

Mercedes-Benz S500 / S550 (W221, M273 V8) • 2005-2011

The M273 V8 uses port injection, so intake-valve carbon is rarely the reason for a single-cylinder m...

Transmission Control System Malfunction

Mercedes C-Class • 2007-2024

The W204 C-Class with the 722.9 (7G-Tronic) transmission often sets P0700 because of a conductor pla...

Output Speed Sensor Circuit Malfunction

Mercedes C-Class (722.9) • 2007-2024

On the W204 and early W205 C-Class with the 722.9 (7G-Tronic) transmission, the output speed sensor ...

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....