Common Audi OBD-II error codes: decoding and potential fixes

BySerge Barrett

Audi vehicles are renowned for their precision engineering and performance, but even these premium machines can encounter issues signaled by the check engine light. OBD-II (On-Board Diagnostics II) codes help diagnose problems across models like the A4, Q5, and TT, covering everything from engine misfires to emission system faults. These codes, starting with P for powertrain, provide clues to faulty sensors, wiring, or components. Understanding them empowers owners to address issues early, potentially avoiding costly repairs. This guide decodes over 80 common codes, drawn from real-world diagnostics, with explanations, causes, and step-by-step solutions. While generic codes apply broadly, Audi-specific ones (often P1xxx) offer deeper insights via tools like VCDS or generic scanners.

How OBD-II codes work in Audi vehicles

Audi’s OBD-II system integrates with the Engine Control Module (ECM) to monitor emissions, fuel efficiency, and performance. When a fault occurs, a code stores in the ECM, illuminating the check engine light. Scanners connect to the port under the dashboard to read codes, which can be pending (intermittent) or confirmed (persistent). Always scan for accompanying symptoms like rough idling or reduced power. Resetting codes without fixes is temporary—the light returns if issues persist. For Audis, enhanced codes reveal specifics, but start with basics: check battery voltage and fuses before diving in. Pro tip: Log codes with mileage for patterns, especially in turbocharged models prone to boost-related faults.

Decoding popular Audi OBD-II codes with solutions

We’ve compiled over 80 codes common in Audis from A3 to Q7, grouped by system. Each includes the code, description, potential causes, and fixes based on typical patterns. Professional tools like Audi’s ODIS may be needed for complex cases, but many are DIY-friendly.

Fuel and air system codes

These involve air intake, fuel delivery, and mixtures, often causing poor economy or hesitation.

  • P000A: “A” Camshaft Position Slow Response Bank 1. Causes: Faulty camshaft actuator or timing chain wear. Fixes: Inspect timing components; replace actuator.
  • P000B: “B” Camshaft Position Slow Response Bank 1. Causes: Similar to P000A; oil contamination. Fixes: Change oil and filter; test actuator.
  • P0087: Fuel Rail/System Pressure Too Low. Causes: Clogged fuel filter or weak pump. Fixes: Replace filter; test pump pressure.
  • P0088: Fuel Rail/System Pressure Too High. Causes: Stuck regulator or faulty sensor. Fixes: Bleed system; replace regulator.
  • P0100: Mass or Volume Air Flow Circuit Malfunction. Causes: Dirty MAF sensor. Fixes: Clean with MAF spray; check intake leaks.
  • P0101: Mass or Volume Air Flow Circuit Range/Performance. Causes: Sensor out of spec. Fixes: Recalibrate or replace MAF.
  • P0102: Mass or Volume Air Flow Circuit Low Input. Causes: Wiring fault. Fixes: Test voltage; repair harness.
  • P0103: Mass or Volume Air Flow Circuit High Input. Causes: Short in circuit. Fixes: Isolate and repair short.
  • P0106: Manifold Abs.Pressure or Bar.Pressure Range/Performance. Causes: Faulty MAP sensor. Fixes: Test MAP; replace if needed.
  • P0107: Manifold Abs.Pressure or Bar.Pressure Low Input. Causes: Low voltage. Fixes: Check sensor wiring.
  • P0108: Manifold Abs.Pressure or Bar.Pressure High Input. Causes: High voltage. Fixes: Repair shorts to power.
  • P0170: Fuel Trim Bank1 Malfunction. Causes: Vacuum leak. Fixes: Smoke test intake; seal leaks.
  • P0171: System Too Lean (Bank 1). Causes: Air leak or faulty O2 sensor. Fixes: Replace O2; check injectors.
  • P0172: System Too Rich (Bank 1). Causes: Clogged injectors. Fixes: Clean ultrasonically.
  • P0174: System Too Lean (Bank 2). Causes: Similar to P0171. Fixes: Symmetric checks for Bank 2.
  • P0175: System Too Rich (Bank 2). Causes: Similar to P0172. Fixes: Focus on Bank 2 components.

Ignition and misfire codes

Common in high-mileage Audis, leading to vibrations or power loss from spark or compression issues.

  • P0300: Random/Multiple Cylinder Misfire Detected. Causes: Worn plugs in TFSI engines. Fixes: Replace plugs; swap coils.
  • P0301: Cylinder 1 Misfire Detected. Causes: Faulty plug or injector. Fixes: Check Cylinder 1 components.
  • P0302: Cylinder 2 Misfire Detected. Causes: Similar. Fixes: Inspect Cylinder 2.
  • P0303: Cylinder 3 Misfire Detected.
  • P0304: Cylinder 4 Misfire Detected.
  • P0305: Cylinder 5 Misfire Detected (V6+ models).
  • P0306: Cylinder 6 Misfire Detected.
  • P0307: Cylinder 7 Misfire Detected (V8).
  • P0308: Cylinder 8 Misfire Detected.
  • P0316: Misfire Detected on Startup. Causes: Cold start issues. Fixes: Test battery; check starter.
  • P0351: Ignition Coil A Primary/Secondary Circuit. Causes: Faulty coil. Fixes: Resistance test; replace.
  • P0352: Ignition Coil B Primary/Secondary Circuit.
  • P0353: Ignition Coil C.
  • P0354: Ignition Coil D.
  • P0355: Ignition Coil E.
  • P0356: Ignition Coil F.

Emission control codes

Tied to catalysts, EGR, and EVAP, essential for emissions tests.

  • P0400: Exhaust Gas Recirculation Flow Malfunction. Causes: Clogged EGR valve. Fixes: Clean or replace valve.
  • P0401: EGR Flow Insufficient Detected. Causes: Hose leak. Fixes: Inspect and seal hoses.
  • P0402: EGR Flow Excessive Detected. Causes: Stuck valve. Fixes: Disassemble and lubricate.
  • P0403: EGR Control Circuit Malfunction. Causes: Wiring fault. Fixes: Check continuity.
  • P0420: Catalyst System Efficiency Below Threshold (Bank 1). Causes: Worn converter. Fixes: Monitor O2; replace cat.
  • P0430: Catalyst System Efficiency Below Threshold (Bank 2). Causes: Similar. Fixes: Confirm no upstream faults; replace.
  • P0440: Evaporative Emission Control System Malfunction. Causes: Loose gas cap. Fixes: Tighten and reset.
  • P0441: EVAP Incorrect Purge Flow. Causes: Faulty purge valve. Fixes: Test solenoid.
  • P0442: EVAP Small Leak Detected. Causes: Cracked hose. Fixes: Smoke test to locate.
  • P0443: EVAP Purge Control Valve Circuit. Causes: Wiring issue. Fixes: Repair circuit.
  • P0455: EVAP Large Leak Detected. Causes: Damaged filler neck. Fixes: Visual inspection.
  • P0456: EVAP Very Small Leak Detected. Causes: O-ring failure. Fixes: Check seals.

Sensor and circuit codes

Sensors track temps, pressures, and positions; failures are frequent in Audis.

  • P0112: Intake Air Temp Circuit Low Input. Causes: Faulty IAT sensor. Fixes: Replace sensor.
  • P0113: Intake Air Temp Circuit High Input. Causes: Similar. Fixes: Replace sensor.
  • P0116: Engine Coolant Temp Circuit Range/Performance. Causes: Stuck thermostat. Fixes: Test coolant flow.
  • P0117: Engine Coolant Temp Circuit Low Input. Causes: Low voltage. Fixes: Replace ECT sensor.
  • P0118: Engine Coolant Temp Circuit High Input. Causes: High voltage. Fixes: Replace sensor.
  • P0120: Throttle/Pedal Position Sensor A Circuit. Causes: Dirty throttle body. Fixes: Clean and recalibrate.
  • P0121: Throttle/Pedal Position Sensor A Range/Performance.
  • P0122: Throttle/Pedal Position Sensor A Low Input.
  • P0123: Throttle/Pedal Position Sensor A High Input.
  • P0130: O2 Sensor Circuit (Bank 1 Sensor 1). Causes: Upstream sensor failure. Fixes: Replace with OEM.
  • P0131: O2 Sensor Circuit Low Voltage (Bank 1 Sensor 1).
  • P0132: O2 Sensor Circuit High Voltage (Bank 1 Sensor 1).
  • P0133: O2 Sensor Circuit Slow Response (Bank 1 Sensor 1).
  • P0134: O2 Sensor Circuit No Activity (Bank 1 Sensor 1).
  • P0135: O2 Sensor Heater Circuit (Bank 1 Sensor 1). Causes: Heater burnout. Fixes: Replace sensor.
  • P0136: O2 Sensor Circuit (Bank 1 Sensor 2).
  • P0137: O2 Sensor Circuit Low Voltage (Bank 1 Sensor 2).
  • P0138: O2 Sensor Circuit High Voltage (Bank 1 Sensor 2).
  • P0140: O2 Sensor Circuit No Activity (Bank 1 Sensor 2).
  • P0141: O2 Sensor Heater Circuit (Bank 1 Sensor 2). Causes: Downstream heater issue. Fixes: Replace sensor.
  • P0150: O2 Sensor Circuit (Bank 2 Sensor 1).
  • P0155: O2 Sensor Heater Circuit (Bank 2 Sensor 1).

Transmission and drivetrain codes

Audi transmissions like Tiptronic can flag shifting problems.

  • P0700: Transmission Control System Malfunction. Causes: TCM issue. Fixes: Scan for sub-codes.
  • P0705: Transmission Range Sensor Circuit (PRNDL Input). Causes: Faulty switch. Fixes: Replace neutral safety switch.
  • P0715: Input/Turbine Speed Sensor Circuit. Causes: Debris on sensor. Fixes: Clean or replace.
  • P0720: Output Speed Sensor Circuit. Causes: Similar; affects speedo. Fixes: Replace sensor.
  • P0730: Incorrect Gear Ratio. Causes: Slipping clutches. Fixes: Change fluid first.
  • P0740: Torque Converter Clutch Circuit. Causes: Solenoid failure. Fixes: Test pressure; replace solenoid.
  • P0750: Shift Solenoid A Malfunction.
  • P0755: Shift Solenoid B Malfunction.
  • P0760: Shift Solenoid C Malfunction.

Audi-specific codes (P1xxx range)

These provide enhanced diagnostics for Audi systems.

  • P1004: Torque Difference Cylinder 1 Limiting Value Exceeded. Causes: Injector imbalance. Fixes: Test injectors; replace faulty one.
  • P1005: Torque Difference Cylinder 2 Limiting Value Exceeded.
  • P1006: Torque Difference Cylinder 3 Limiting Value Exceeded.
  • P1007: Torque Difference Cylinder 4 Limiting Value Exceeded.
  • P1009: Air Mass Meter 1/2 Implausible Signal. Causes: Faulty MAF. Fixes: Replace MAF sensors.
  • P1103: O2 Sensor Circuit (Bank 1-Sensor 1) Output Too Low. Causes: Lean mixture. Fixes: Check for exhaust leaks.
  • P1111: O2 Control (Bank 1) System Too Lean.
  • P1113: O2 Control (Bank 1 Sensor 1) Internal Resistance Too High. Causes: Aged sensor. Fixes: Replace O2 sensor.
  • P1127: Long Term Fuel Trim Add. Air Bank 1 System Too Rich. Causes: Rich condition. Fixes: Check fuel pressure.
  • P1128: Long Term Fuel Trim Add. Air Bank 1 System Too Lean.
  • P1136: Long Term Fuel Trim Add. Fuel Bank 1 System Too Lean.
  • P1137: Long Term Fuel Trim Add. Fuel Bank 1 System Too Rich.
  • P1141: Load Calculation Cross Check Range/Performance. Causes: Throttle adaptation. Fixes: Perform adaptation.
  • P1154: Manifold Switch Over Malfunction. Causes: Faulty actuator. Fixes: Replace intake manifold runner actuator.
  • P1171: Throttle Actuation Potentiometer Sign.2 Range/Performance.
  • P1176: O2 Correction Behind Catalyst B1 Limit Attained. Causes: Faulty cat. Fixes: Replace catalytic converter.
  • P1196: O2 Sensor Heater Circuit (Bank 1-Sensor 1) Electrical Malfunction.
  • P1198: O2 Sensor Heater Circuit (Bank 1-Sensor 2) Electrical Malfunction.
  • P1296: Cooling System Malfunction. Causes: Thermostat failure. Fixes: Replace thermostat.
  • P1297: Connection Turbocharger/Throttle Valve Pressure Hose. Causes: Hose leak. Fixes: Inspect and replace hose.
  • P1300: Misfire Detected Low Fuel. Causes: Low fuel level. Fixes: Refuel; check pump.
  • P1336: Engine Torque Monitoring Control Limit Exceeded. Causes: Overboost. Fixes: Check turbo controls.
  • P1337: Camshaft Position Sensor (Bank 1) Short to Ground.
  • P1338: Camshaft Position Sensor (Bank 1) Open/Short to B+.
  • P1340: Crankshaft Position/Camshaft Sensor Signal Out of Sequence.
  • P1391: Camshaft Position Sensor (Bank 2) Short to Ground.
  • P1392: Camshaft Position Sensor (Bank 2) Open/Short to B+.
  • P1400: EGR Valve Circuit Electrical Malfunction.
  • P1401: EGR Valve Circuit Short to Ground.
  • P1402: EGR Valve Circuit Short to B+.
  • P1424: Secondary Air Injector System (Bank 1) Leak Detected. Causes: Leak in AIR system. Fixes: Smoke test; repair leak.
  • P1470: EVAP Emission Control LDP Circuit Electrical Malfunction.
  • P1476: EVAP Emission Control LDP Circuit Malfunction/Insufficient Vacuum.
  • P1500: Fuel Pump Relay Circuit Electrical Malfunction.
  • P1502: Fuel Pump Relay Circuit Short to B+.
  • P1519: Intake Manifold Runner Control Stuck Closed. Causes: Stuck flap. Fixes: Clean or replace actuator.
  • P1522: Intake Camshaft Control (Bank 2) Malfunction.

That’s over 80 codes with insights from Audi repairs. Patterns like multiple sensor codes often point to wiring harness issues in older models.

Advanced tips for Audi owners

Approach diagnostics methodically: Use a VCDS scanner for Audi-specific data, capturing freeze frames for context. Intermittent codes? Monitor live data during drives. Turbo models like the S3 may trigger boost codes from modified intakes—revert to stock for testing. Update ECM software at dealers for known glitches. Preventive maintenance, like timely oil changes with Audi-spec fluids, averts many codes. Hands-on owners: Stock a multimeter and fuse puller—it’s your gateway to self-reliance, keeping that signature Audi drive intact for miles ahead.

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