Mercedes-Benz Diagnostic Trouble Codes
OBD2 fault codes seen on Mercedes-Benz vehicles, with what each code means and the Mercedes-Benz models it shows up on. Each code's page has its typical repair cost range.
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Crankshaft Position - Camshaft Position Correlation (Bank 1 Sensor B)
- Mercedes E-Class • 2011-2016
The W212 E-Class used the M276 3.5 V6 (biturbo in the E 400) and the M278 4.7 V8 biturbo (E 500) between…
Crankshaft Position - Camshaft Position Correlation (Bank 2 Sensor A)
- Mercedes E-Class • 2011-2016
P0018 is a bank 2 timing fault, so it applies to the V engines of the W212 E-Class: the M276 3.5 V6 (biturbo…
Crankshaft Position - Camshaft Position Correlation (Bank 2 Sensor B)
- Mercedes E-Class • 2011-2020
On the M276 V6, check the bank 2 camshaft adjuster magnet and its connector first, before suspecting the…
Camshaft Position Sensor "A" Circuit Low Input (Bank 1 or Single Sensor)
- Mercedes C-Class • 2007-2024
Camshaft Position Sensor "A" Circuit High Input (Bank 1 or Single Sensor)
- Mercedes C-Class • 2007-2024
Emissions
"A" Camshaft Position - Timing Over-Advanced or System Performance (Bank 2)
- Mercedes E-Class • 2011-2020
P0021 on an E-Class needs a V engine: the M276 V6 (3.0 turbo or 3.5, 2011-2020) or the M278 4.7 V8 in the E…
"A" Camshaft Position - Timing Retarded (Bank 2)
- Mercedes E-Class • 2011-2020
The M276 V6 of the E-Class (W212 from 2011, W213 from 2016) has variable valve timing on all four camshafts…
"B" Camshaft Position: Timing Over-Advanced or System Performance (Bank 2)
- Mercedes-Benz E-Class E 350 (M272 3.5 V6) • 2005-2011
The M272 3.5 V6 has variable valve timing on both the intake and exhaust camshafts, each adjustable through…
O2 Sensor Circuit Malfunction (Bank 1, Sensor 2)
- Mercedes C-Class • 2007-2010
The W204 C 180 Kompressor and C 200 Kompressor (from 2007) use the supercharged 1.8 litre M271 petrol engine…
O2 Sensor Circuit Low Voltage (Bank 1, Sensor 2)
- Mercedes C-Class • 2007-2010
The W204 C 180 Kompressor and C 200 Kompressor (from 2007) use the supercharged 1.8 litre M271 petrol engine…
O2 Sensor Circuit High Voltage (Bank 1, Sensor 2)
- Mercedes C-Class • 2007-2011
On the W204 C-Class with the M271 1.8 Kompressor petrol, P0138 is either a genuine rich condition (check fuel…
O2 Sensor Circuit Slow Response (Bank 1, Sensor 2)
- Mercedes C-Class • 2007-2011
On the W204 C-Class with the M271 1.8 Kompressor petrol, P0139 can be the downstream sensor ageing on a…
O2 Sensor Circuit No Activity Detected (Bank 1, Sensor 2)
- Mercedes C-Class • 2007-2010
The W204 C 180 Kompressor and C 200 Kompressor (from 2007) use the supercharged 1.8 litre M271 petrol engine…
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 the…
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 the…
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 the…
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 the…
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 the…
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 the…
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 before and…
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 travel…
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 (bank 2)…
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-hand…
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 connector of…
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 sensor on the…
Exhaust Gas Recirculation Flow Excessive Detected
- Mercedes Sprinter • 2009-2022
The Sprinter used the 2.1 litre OM651 diesel in its second generation and, until 2022, in its third. P0402 is…
Exhaust Gas Recirculation Control Circuit Malfunction
- Mercedes Sprinter • 2009-2022
Engine covered (diesel): 2.1 litre OM651 four-cylinder. P0403 reports a fault in the circuit that controls…
Exhaust Gas Recirculation Control Circuit Range/Performance
- Mercedes Sprinter • 2009-2022
The Sprinter used the 2.1 litre OM651 diesel in its second generation and, until 2022, in its third. P0404 is…
Exhaust Gas Recirculation Sensor "A" Circuit Low
- Mercedes Sprinter • 2009-2022
The Sprinter 2.1 CDI diesel is the OM651, and the code refers to the position sensor of its EGR valve.
Exhaust Gas Recirculation Sensor "A" Circuit High
- Mercedes Sprinter • 2010-2024
On the Sprinter, if the EGR sensor wiring is damaged or corroded at the connector, replace the connector or…
Warm Up Catalyst Efficiency Below Threshold (Bank 1)
- Mercedes-Benz E-Class • 2011-2016
On the W212 E-Class with the M276 V6 or M278 V8, P0421 points to the bank 1 pre-cat. If cam-timing or misfire…
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 cat in the…
Catalyst System Efficiency Below Threshold (Bank 2)
- Mercedes-Benz C-Class • 2007-2023
Only the V6 and V8 C-Class models have a second cylinder bank and can set P0430, for example the C 280 and C…
Warm Up Catalyst Efficiency Below Threshold (Bank 2)
- Mercedes-Benz E-Class • 2011-2020
On the W212 and W213 E-Class with the M276 V6, check for Bank 2 lean codes such as P0174 and for misfire…
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 main cat…
Heated Catalyst Temperature Below Threshold (Bank 2)
- Mercedes-Benz E-Class • 2020-2024
On the W213 facelift E-Class, only the M177 V8 in the E63 is a two-bank engine and can set a genuine P0434…
NOx Sensor Circuit (Bank 1)
- Mercedes-Benz C 220 d BlueTEC (W205) • 2014-2021
A German workshop article on BlueTEC diesels (the Mercedes OM651 and OM654 among them) says NOx sensors sit…
Diesel Particulate Filter Differential Pressure Too Low (Bank 1)
- Mercedes-Benz Sprinter • 2006-2018
The W906 Sprinter (2006 to 2018) offered the 2.1 litre OM651 and the 3.0 litre V6 OM642 diesel engines. A…
Diesel Particulate Filter Differential Pressure Too High (Bank 1)
- Mercedes-Benz Sprinter • 2006-2018
Sprinter OM651 and OM642 filters load up faster on vans doing stop-start delivery work, because the exhaust…
Particulate Matter Sensor Temperature Circuit
- Mercedes-Benz C-Class diesel • 2018-2021
- Mercedes-Benz GLC 220d / 250d • 2017-2020
Fuel System
Fuel Trim Malfunction (Bank 1)
- Mercedes C-Class • 2007-2019
The W204 C-Class four-cylinder petrols were the 1.8 litre M271 (supercharged from 2007, turbo CGI from 2009)…
Fuel Trim Malfunction (Bank 2)
- Mercedes E-Class • 2011-2016
On the W212 E-Class with the M276 V6, check the Bank 2 upstream lambda sensor.
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 and the AMG…
System Too Rich (Bank 2)
- Mercedes E-Class • 2012-2016
On the W212 E 350 with the M276 V6, P0175 refers to bank 2, so compare the fuel trims of both banks before…
Fuel Rail Pressure Sensor Circuit Range/Performance
- Mercedes C-Class • 2008-2021
The 2.0 L M274 turbo petrol in the W205 C-Class (from 2014) uses direct injection. The OM651 diesel, built…
Injector Circuit / Open - Cylinder 1
- Mercedes C-Class • 2014-2021
The W205 C-Class used the OM651 diesel until 2018 and the OM654 after it, with mainly M274 and M264…
Injector Circuit / Open - Cylinder 2
- Mercedes C-Class • 2007-2024
The OM651 diesel, built since 2008, has common-rail injection. Delphi states that replacement common-rail…
Injector Circuit / Open - Cylinder 3
- Mercedes C-Class • 2007-2024
The OM651 diesel, built since 2008, has common-rail injection. Delphi states that replacement common-rail…
Injector Circuit / Open - Cylinder 4
- Mercedes C-Class • 2007-2024
On the OM651 CDI diesel a replacement common-rail injector has to be programmed to the car, a job for XENTRY…
Injector Circuit / Open - Cylinder 5
- Mercedes C-Class • 2007-2014
In the W204 C-Class only the V6 and V8 engines have a cylinder 5: the petrol M272 and M276, the M156 V8 of…
Injector Circuit / Open - Cylinder 6
- Mercedes C-Class • 2007-2021
V6 petrol (M272, M276) and V6 diesel (OM642) C-Class variants have a cylinder 6.
Electrical
Engine Oil Temperature Sensor
- Mercedes-Benz C-Class • 2005-2024
Engine Oil Temperature Sensor Range/Performance
- Mercedes-Benz C-Class • 2001-2007 (W203)
Mercedes fits an oil level sensor (B40) in the oil pan that reports oil level, oil temperature and oil…
Glow Plug / Heater Circuit "A" Malfunction
- Mercedes-Benz (OM651 diesel) • 2008-2016 (C-Class W204, E-Class W212)
The OM651 four-cylinder diesel uses a glow plug control module that the ECU monitors for circuit faults…
Brake Switch "A"/"B" Correlation
- Mercedes C-Class • 2008-2024
On the C-Class the brake switch signal is also used by the cruise control and the start-stop system, which…
ECM/PCM Processor Fault
- Mercedes C-Class • 2007-2024
Inspect for water marks and green corrosion on the connector before condemning the module, since drying and…
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. Verify supply voltage and…
Cylinder 1 Glow Plug Circuit
- Mercedes-Benz (OM651 diesel) • 2008-2018
On the OM651, P0671 refers to the cylinder 1 glow plug circuit. Check the plug and its wiring and connector…
Cylinder 2 Glow Plug Circuit
- Mercedes-Benz (OM651 diesel) • 2008-2018
The OM651 is a four-cylinder common-rail diesel, built since 2008.
Cylinder 3 Glow Plug Circuit
- Mercedes-Benz (OM651 diesel) • 2008-2018
The OM651 is a four-cylinder common-rail diesel, built since 2008.
Cylinder 4 Glow Plug Circuit
- Mercedes-Benz (OM651 diesel) • 2008-2018
Engine covered (diesel): 2.1 litre OM651 four-cylinder. Mercedes per-plug data beyond the generic code is…
Misfire
Cylinder 4 Misfire Detected
- Mercedes C-Class • 2014-2018
The C 200 and C 250 (W205) use the M274, a 2.0-litre turbocharged four-cylinder engine with direct injection.
Cylinder 6 Misfire Detected
- Mercedes C-Class • 2007-2010
W204 C350 with the M272 V6 can log P0306 from a worn cylinder 6 ignition coil or spark plug.
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 the usual…
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 misfire…
Transmission
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 plate fault…
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 (Y3/8n3)…
Torque Converter Clutch Circuit Performance/Stuck Off
- Mercedes C-Class • 2007-2011
The W204 C 320 CDI is fitted with the 7G-Tronic (722.9) automatic, whose torque converter lock-up clutch…
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