Audi Diagnostic Trouble Codes
OBD2 fault codes seen on Audi vehicles, with what each code means, its typical repair cost range, and notes on specific Audi models.
Emissions
Camshaft Position B - Timing Over-Advanced or System Performance (Bank 1)
Audi A4 • 2008-2024
On the Audi A4, the EA888 1.8 TFSI and 2.0 TFSI engines are well known for timing chain tensioner an...
"B" Camshaft Position - Timing Over-Retarded (Bank 1)
Audi A4 • 2008-2024
The 2.0 TFSI (EA888) engine uses an exhaust camshaft adjuster that can fail due to oil sludge or a w...
"A" Camshaft Position - Timing Over-Advanced or System Performance (Bank 2)
Audi A6 • 2005-2024
The A6 3.0 TFSI EA837 supercharged V6 commonly sets P0021 around 100,000 to 150,000 km due to bank 2...
"A" Camshaft Position - Timing Retarded (Bank 2)
Audi A6 • 2005-2024
The A6 3.0 TFSI EA837 supercharged V6 is the prime P0022 candidate. Bank 2 intake adjuster failure o...
Intake Air Temperature Sensor 2 Circuit High
Audi A4 • 2008-2024
The A4 uses the same VAG combined charge air pressure and temperature sensor as the Golf on its EA88...
Manifold Absolute Pressure/Barometric Pressure Circuit Low
Audi A4 • 2008-2024
The A4 shares its sensor design with the Golf, the same VAG G71 intake manifold pressure sender comb...
O2 Sensor Heater Circuit Malfunction (Bank 1, Sensor 1)
Audi A4 • 2008-2024
The A4 shares the EA888 family with the Golf, so the upstream Bosch sensor lives in the hot turbo do...
O2 Sensor Circuit Malfunction (Bank 1, Sensor 2)
Audi A4 • 2006-2024
On the B7 and B8 A4 with the 2.0 TFSI (EA113 in the B7, EA888 in the B8), oil consumption on some EA...
O2 Sensor Circuit Low Voltage (Bank 1, Sensor 2)
Audi A4 • 2006-2024
On the B7 and B8 A4 2.0 TFSI (EA113 in the B7, EA888 in the B8), oil consumption on some EA888 engin...
O2 Sensor Circuit High Voltage (Bank 1, Sensor 2)
Audi A4 • 2006-2024
On the B7 and B8 A4 2.0 TFSI (EA113 in the B7, EA888 in the B8), check fuel trims and injector condi...
O2 Sensor Circuit Slow Response (Bank 1, Sensor 2)
Audi A4 • 2006-2024
The B8 A4 with the 2.0 TFSI (EA888) shares that family's oil consumption pattern, which can coat the...
O2 Sensor Circuit No Activity Detected (Bank 1, Sensor 2)
Audi A4 • 2006-2024
On the B7 and B8 A4 with 2.0 TFSI, the downstream sensor connector sits in a tight spot and can be d...
O2 Sensor Circuit Malfunction (Bank 2, Sensor 2)
Audi A6 • 2004-2009
The 3.2 V6 FSI in the C6-generation A6 has four oxygen sensors: two ahead of the catalytic converter...
O2 Sensor Circuit Low Voltage (Bank 2, Sensor 2)
Audi A6 • 2004-2009
On the 3.2 V6 FSI each bank's three cylinders feed their own cast-iron exhaust manifold, and the ban...
O2 Sensor Circuit High Voltage (Bank 2, Sensor 2)
Audi A6 • 2004-2009
The 3.2 V6 FSI runs separate oxygen sensing for each bank, so a rich condition on the bank 2 cylinde...
O2 Sensor Circuit Slow Response (Bank 2, Sensor 2)
Audi A6 • 2004-2009
The downstream G131 sensor is how the engine computer judges the bank 2 catalyst on the 3.2 V6 FSI. ...
O2 Sensor Circuit No Activity Detected (Bank 2, Sensor 2)
Audi A6 • 2004-2009
On the 3.2 V6 FSI the bank 2 post-catalyst sensor is G131 and the bank 1 one is G130. With no activi...
O2 Sensor Heater Circuit Malfunction (Bank 2, Sensor 2)
Audi A6 • 2004-2009
Audi's service training for the A6 3.2 V6 FSI lists a separate heater for each of its four oxygen se...
Exhaust Gas Recirculation (EGR) Flow Insufficient
Audi A4 • 2005-2024
The A4 shares VW Group TDI and TFSI hardware, so the 2.0 TDI is the most common P0401 vehicle here, ...
Exhaust Gas Recirculation Flow Excessive Detected
Audi A4 • 2008-2024
The A4 2.0 TDI (B8 and B9 chassis) shares EA189 and EA288 engines with the Golf and suffers identica...
Exhaust Gas Recirculation Control Circuit Malfunction
Audi A4 • 2008-2024
B8 and B9 A4 2.0 TDI models share the EA189/EA288 EGR valve with the Golf, so failure modes are iden...
Exhaust Gas Recirculation Control Circuit Range/Performance
Audi A4 • 2008-2024
The A4 2.0 TDI (B8, B9) shares the EA189 and EA288 EGR setup with the Golf, so P0404 has identical r...
Exhaust Gas Recirculation Sensor "A" Circuit Low
Audi A4 • 2008-2024
B8 and B9 A4 2.0 TDI models share the EGR sensor failure modes with the Golf. The B8 has tighter pac...
Exhaust Gas Recirculation Sensor "A" Circuit High
Audi A4 • 2008-2024
B8 and B9 A4 2.0 TDI suffer the same P0406 failure modes as the Golf, plus restricted access due to ...
Secondary Air Injection System Malfunction
Audi A4 • 2005-2020
The 2.0 TFSI in the B7 and B8 A4 shares the VW secondary air system. The combination valve is the mo...
Secondary Air Injection System Incorrect Flow Detected
Audi A3 • 2005-2024
The A3 uses the same MQB platform secondary air system as the Golf on 2013+ models. The 2.0 TFSI in ...
Warm Up Catalyst Efficiency Below Threshold (Bank 1)
Audi A6 • 2005-2024
The Audi A6 3.0 TFSI (EA837 supercharged V6) has separate pre-cats per bank, and P0421 specifically ...
Main Catalyst Efficiency Below Threshold (Bank 1)
Audi A6 • 2005-2024
The Audi A6 3.0 TFSI (EA837) runs separate main cats per bank. On Bank 1, the bank containing cylind...
Catalyst System Efficiency Below Threshold (Bank 2)
Audi A4 • 2005-2024
Four-cylinder TFSI A4 models are single-bank and rarely see P0430. The fault is most relevant on the...
Warm Up Catalyst Efficiency Below Threshold (Bank 2)
Audi A6 • 2005-2024
On the Audi A6 3.0 TFSI (EA837 supercharged V6) and 3.0 TDI V6, P0431 points to the Bank 2 pre-cat, ...
Main Catalyst Efficiency Below Threshold (Bank 2)
Audi A6 • 2005-2024
On the Audi A6 3.0 TFSI (EA837) V6 each bank has its own catalysts, and P0432 points to the Bank 2 m...
Heated Catalyst Temperature Below Threshold (Bank 2)
Audi A6 • 2019-2024
The C8 A6 3.0 TFSI (EA839 V6 mild-hybrid) and 3.0 TDI mild-hybrid set P0434 most often after winter ...
Diesel Particulate Filter Efficiency Below Threshold (Bank 2)
Audi Q7 V8 and V12 TDI • 2007-2015
The 4.2 TDI V8 fitted to the Q7 is documented with two silicon carbide particulate filters, and the ...
Diesel Particulate Filter Efficiency Below Threshold (Bank 2)
Audi A8 4.2 TDI • 2005-2010
The common-rail 4.2 TDI V8 in the A8 runs two close-coupled oxidation catalysts and two silicon carb...
O2 Sensor Signal Biased/Stuck Lean (Bank 1, Sensor 1)
Audi A4 • 2008-2024
The 2.0 TFSI A4 shares the lean-code tendency of the wider VAG range. PCV diaphragm failure and a cr...
Exhaust Gas Temperature Sensor Circuit Range/Performance (Bank 1 Sensor 4)
Audi A4 2.0 TDI • 2008-2015
On some B8 A4 2.0 TDI engines outside North America (engine code CAGA), the exhaust temperature read...
Ignition
Crankshaft Position - Camshaft Position Correlation (Bank 1 Sensor B)
Audi A6 • 2005-2024
The 3.0 TFSI EA837 supercharged V6 in the A6 is known for camshaft adjuster and timing chain tension...
Crankshaft Position - Camshaft Position Correlation (Bank 2 Sensor A)
Audi A6 • 2005-2024
The 3.0 TFSI EA837 supercharged V6 and the 4.2 FSI V8 are the typical P0018 candidates in the A6 lin...
Crankshaft Position - Camshaft Position Correlation (Bank 2 Sensor B)
Audi A6 • 2005-2024
The A6 3.0 TFSI EA837 supercharged V6 sets P0019 frequently around 100,000 to 150,000 km. The bank 2...
Knock Sensor 1 Circuit High Input (Bank 1 or Single Sensor)
Audi A4 • 2008-2024
B8 A4 with the 2.0 TFSI tends to log P0328 from harness chafing near the engine cover mounting bolt....
Camshaft Position Sensor Circuit Malfunction
Audi A4 • 2008-2024
The Audi A4 shares the EA888 2.0 TFSI and the 3.0 TFSI V6 with much of the VAG range. CMP sensors ar...
Camshaft Position Sensor "A" Circuit Range/Performance
Audi A4 • 2005-2024
The 2.0 TFSI in B7 and early B8 A4s uses a timing chain at the rear of the engine, making replacemen...
Camshaft Position Sensor "A" Circuit Low Input (Bank 1 or Single Sensor)
Audi A4 • 2008-2024
B8 A4 with the 2.0 TFSI commonly sets P0342 alongside P0011/P0012 when the cam adjuster oil control ...
Camshaft Position Sensor "A" Circuit High Input (Bank 1 or Single Sensor)
Audi A4 • 2008-2024
B8 A4 with 2.0 TFSI sometimes logs P0343 after a heat-soak start. The cam sensor fails intermittentl...
Ignition Coil E Primary/Secondary Circuit Malfunction
Audi S5 Coupe (B8, 4.2 FSI V8) • 2007-2012
The 4.2 FSI V8 is direct-injected, and its other well-known misfire cause, carbon building up on the...
Ignition Coil F Primary/Secondary Circuit Malfunction
Audi S5 Coupe (B8, 4.2 FSI V8) • 2007-2012
The 4.2 FSI V8 is direct-injected, and its other well-known misfire cause, carbon building up on the...
Ignition Coil G Primary/Secondary Circuit Malfunction
Audi S5 Coupe (B8, 4.2 FSI V8) • 2007-2012
The 4.2 FSI V8 is direct-injected, and its other well-known misfire cause, carbon building up on the...
Ignition Coil H Primary/Secondary Circuit Malfunction
Audi S5 Coupe (B8, 4.2 FSI V8) • 2007-2012
The 4.2 FSI V8 is direct-injected, and its other well-known misfire cause, carbon building up on the...
Fuel System
Turbocharger/Supercharger Boost Control "A" Circuit Range/Performance
Audi A4 • 2016-2019
The B9 A4 with the 2.0 TFSI petrol uses the third-generation EA888, whose turbo wastegate is moved b...
Mass or Volume Air Flow Circuit Low Input
Audi A4 • 2008-2024
The B8 A4 2.0 TFSI uses the same Bosch hot-film MAF design as the Golf, and the element loses sensit...
Mass or Volume Air Flow Circuit High Input
Audi A4 • 2008-2024
B8 A4 2.0 TFSI shares the EA888 MAF setup with the Golf and exhibits identical P0103 patterns. Restr...
Mass or Volume Air Flow Circuit Intermittent
Audi A4 • 1997-2024
Audi uses the same Volkswagen Group fault list, so VCDS reports P0104 as 16488 against the G70 air m...
System Too Lean (Bank 1)
Audi A4 • 2008-2024
The A4 shares the EA888 family with the Golf, so the PCV and oil separator diaphragm is the prime P0...
System Too Rich (Bank 1)
Audi A4 • 2008-2024
The 2.0 TFSI EA888 in the B8 and B9 A4 shares the VW purge valve weakness and is also prone to carbo...
Fuel Trim Malfunction (Bank 2)
Audi A6 • 2011-2024
The C7 A6 3.0 TFSI (EA837) is a supercharged V6 with its two cylinder banks on the left and right of...
System Too Lean (Bank 2)
Audi A4 • 2005-2024
Four-cylinder TFSI A4 models are single-bank and set P0171; P0174 shows up on the V6 cars such as th...
System Too Rich (Bank 2)
Audi A6 • 2011-2024
On the C7 A6 with the 3.0 TFSI, a purge valve stuck open adds fuel vapour to the intake and pushes t...
Intake Manifold Runner Control Stuck Open (Bank 1)
Audi A4 • 2005-2024
The A4 B7 and B8 with the 2.0 TFSI engine shares the same intake manifold design as the Golf and is ...
Intake Manifold Runner Control Stuck Closed (Bank 1)
Audi A3 • 2004-2024
The A3 shares its engine and intake manifold with the VW Golf. The 2.0 TDI (BKD/BMM engine codes) in...
Intake Manifold Runner Position Sensor/Switch Circuit Range/Performance (Bank 1)
Audi A3 • 2008-2013
The A3 8P with the 2.0 TDI common-rail engine shares its intake manifold and flap arrangement with t...
System Too Lean at Idle (Bank 1)
Audi A3 • 2005-2024
The A3 with 1.4 TFSI and 2.0 TFSI engines shares the same PCV and vacuum leak issues as the VW Golf....
Cooling System
Electrical
Engine Oil Temperature Sensor
Audi A4 • 2005-2024
The A4 uses the same VW Group oil level and temperature sensor as the Golf, the G266 in the undersid...
Engine Oil Temperature Sensor Range/Performance
Audi A4 • 2005-2024
The A4 uses the same G266 oil level and temperature sensor in the oil pan as the rest of the VW grou...
Engine Overspeed Condition
Audi A3 • 2008-2024
Shares the DSG/S-tronic transmission with the VW Golf. P0219 on automatic A3 models is usually DSG-r...
Knock Sensor 1 Circuit Low Input (Bank 1 or Single Sensor)
Audi A4 • 2005-2024
The B8 A4 with the 2.0 TFSI EA888 has knock sensors mounted under the intake manifold, similar to V6...
Glow Plug / Heater Circuit "A" Malfunction
Audi A4 TDI • 2004-2019
The A4 TDI shares VAG glow plug architecture with the Golf and uses a monitoring control module. P03...
Brake Switch "A"/"B" Correlation
Audi A4 • 2008-2024
B8 A4 owners frequently report P0504 from a sticking brake switch plunger. The plastic plunger swell...
ECM/PCM Processor Fault
Audi A4 • 2005-2024
B7, B8, and B9 A4 models use Simos and MED17 ECUs that can log P0606 after voltage problems, so chec...
Glow Plug Control Module Circuit
Audi A4 TDI • 2004-2019
The A4 TDI shares the VAG monitoring control module with the Golf and Passat. P0670 typically points...
Cylinder 1 Glow Plug Circuit
Audi A4 TDI • 2004-2019
The A4 TDI uses the same VAG per-plug monitoring as the Golf, so P0671 isolates cylinder 1. Some 2.0...
Cylinder 2 Glow Plug Circuit
Audi A4 TDI • 2004-2019
The A4 TDI uses the same VAG per-plug monitoring as the Golf, so P0672 isolates cylinder 2. Some 2.0...
Cylinder 3 Glow Plug Circuit
Audi A4 TDI • 2004-2019
The A4 TDI uses the same VAG per-plug monitoring as the Golf, so P0673 isolates cylinder 3. Some 2.0...
Cylinder 4 Glow Plug Circuit
Audi A4 TDI • 2004-2019
The A4 TDI uses the same VAG per-plug monitoring as the Golf, so P0674 isolates cylinder 4. Some 2.0...
Intake Manifold Runner Control Circuit/Open (Bank 1)
Audi A4 • 2005-2024
The A4 B7/B8 with the 2.0 TFSI engine has the actuator connector in a particularly tight location th...
Misfire
Random/Multiple Cylinder Misfire Detected
Audi A4 • 2008-2024
The A4 shares the EA888 family with the Golf, so intake-valve carbon on direct-injection 2.0 TFSI en...
Cylinder 1 Misfire Detected
Audi A4 • 2008-2024
The A4 shares the EA888 TSI family with VW, so cylinder-1 misfires often trace to intake-valve carbo...
Cylinder 2 Misfire Detected
Audi A4 • 2005-2024
The 2.0 TFSI (EA888) engine in B8 and B9 A4 models is prone to carbon buildup on intake valves due t...
Cylinder 6 Misfire Detected
Audi A6 • 2011-2024
C7 A6 with the 3.0 TFSI supercharged V6 can set P0306 from a cylinder 6 coil, spark plug or injector...
Cylinder 7 Misfire Detected
Audi S5 Coupe (B8, 4.2 FSI V8) • 2007-2012
The 4.2 FSI V8 injects fuel directly into the cylinders, so no fuel washes over the intake valves an...
Cylinder 8 Misfire Detected
Audi S5 Coupe (B8, 4.2 FSI V8) • 2007-2012
Because the 4.2 FSI injects fuel straight into the cylinders, its intake valves collect carbon that ...
EVAP System
Evaporative Emission Control System Malfunction
Audi A4 • 2005-2024
The B7 A4 with the 2.0 TFSI (EA113) and the B8 with the 2.0 TFSI (EA888) commonly trigger P0440 when...
Evaporative Emission Control System Vent Control Circuit Open
Audi A4 • 2005-2024
On A4s with leak-detection hardware, the EVAP vent valve at the canister is the usual failure for P0...
Evaporative Emission Control System Vent Control Circuit Shorted
Audi A4 • 2005-2024
On A4s with leak-detection hardware, the vent valve harness runs under the car, and P0448 often foll...
Evaporative Emission Control System Vent Valve/Solenoid Circuit Malfunction
Audi A4 • 2005-2024
On A4s with leak-detection hardware, the harness routing on the saloon differs slightly from the Gol...
Evaporative Emission Control System Pressure Sensor Intermittent
Audi A4 • 2005-2024
On A4s with leak-detection hardware, the fuel tank pressure sensor is fitted at the fuel pump module...
Evaporative Emission Control System Leak Detected (Fuel Cap Loose/Off)
Audi A4 • 2005-2024
The A4 cap, like the Golf's, must be turned until it clicks, and a cap not seated properly at refuel...
Transmission
Input/Turbine Speed Sensor Circuit Malfunction
Audi A4 • 2005-2024
The A4 with Multitronic CVT (B7/B8) and S-Tronic DSG uses speed sensors that can fail due to metalli...
Torque Converter Clutch Circuit Performance/Stuck Off
Audi A4 • 2005-2024
Only A4s with a torque-converter automatic (tiptronic) can set P0741. The B8, for example, offered a...
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