Volkswagen Fault Codes — Real Causes, Fixes & UK Costs

What Volkswagen codes (P0299, P0171, P0341, P2015, P0420, P0401) actually mean on Volkswagen engines — the real cause, the common misdiagnosis, and the honest UK repair cost.

These are the OBD fault codes we see most often on Volkswagen vehicles in the workshop, with the real cause on Volkswagen engines rather than the generic textbook definition, plus the honest independent-garage cost.

Volkswagen fault codes explained

• P0299 — Turbo underboost on VW — on 1.4 TSI and 2.0 TFSI it's commonly the wastegate actuator; on 2.0 TDI it's the N75 valve or VGT actuator. Typical UK cost £250–£1600.
• P0171 — System too lean (Bank 1) on VW — PCV diaphragm in the rocker cover is the #1 cause across the TSI/TFSI family. Typical UK cost £150–£350.
• P0341 — Camshaft position sensor 'A' range/performance — on 2.0 TDI it's almost always a stretched timing chain or worn cam follower. Typical UK cost £600–£2500.
• P2015 — Intake manifold flap fault on VW 2.0 TDI CR — the lever inside the plastic manifold snaps. Identical fix to Audi/Skoda siblings. Typical UK cost £320–£700.
• P0420 — Catalyst efficiency on VW — on EA888 TSI engines, oil consumption damages the cat genuinely. On older EA113 it's frequently a rear lambda drift. Typical UK cost £150–£1100.
• P0401 — EGR flow insufficient on VW TDI engines — almost always a clogged EGR cooler/valve on PD and CR diesels in stop-start UK driving. Typical UK cost £180–£720.
• P0203 — Injector circuit malfunction Cylinder 3 on VW — common on 1.6/2.0 TDI CR engines, usually a failing piezo injector or harness connector. Typical UK cost £220–£850.
• P0106 — MAP sensor range/performance on VW TSI/TDI — boost-pressure sensor failure is common, plus charge-pipe leaks on 1.4/2.0 TSI. Typical UK cost £100–£320.
• P0562 — System voltage low on VW — battery or alternator failure, with battery-coding via VCDS essential on any post-2011 Golf/Passat. Typical UK cost £100–£420.
• P0100 — MAF circuit malfunction on VW — Bosch HFM5/HFM7 sensor failures across TDI/TSI; intake leaks are a common alternative cause. Typical UK cost £100–£320.
• P0304 — Cylinder 4 misfire on VW — TSI coil pack failure very common; TDI injector or glow plug; older PD diesels injector loom. Typical UK cost £100–£580.
• P0300 — Random misfire on VW group petrols — on 1.4 TSI it's nearly always the timing chain tensioner, on 2.0 TFSI it's coils or carbon. Typical UK cost £150–£1800.
• P0016 — Crank/cam correlation on VW 1.4 TSI EA111 and 2.0 TDI CR — chain stretch (petrol) or timing belt jump (diesel). Typical UK cost £700–£2400.
• P0606 — PCM processor fault on VW — on DSG/S-tronic cars it's usually the mechatronic unit, on petrol/diesels it can be a corroded ECU connector. Typical UK cost £180–£2200.
• P0087 — Fuel rail pressure too low on VW 2.0 TDI common-rail — HP pump (CP4) failure and lift-pump issues are the headline causes. Typical UK cost £220–£4500.
• P2463 — DPF soot accumulation on VW Group 2.0 TDI — the EA189/EA288 engines log this when active regens can't complete. Typical UK cost £120–£2200.
• P0455 — EVAP system gross leak on VW — N80 purge solenoid failure is the headline cause across the TSI range. Typical UK cost £30–£280.
• P0128 — Coolant temp below thermostat regulating temperature on VW — stuck-open thermostat is the near-universal cause. Typical UK cost £140–£480.
• P2002 — DPF efficiency below threshold on VW — substrate damage after failed regens or post-dieselgate software complications. Typical UK cost £220–£2400.
• P0017 — Crank to exhaust cam correlation on VW — 1.4 TSI EA111 chain stretch or 2.0 TDI CR belt jump. Typical UK cost £700–£2400.
• P0301 — Cylinder 1 misfire on VW — coil pack failure on TSI is the headline cause, carbon build-up on higher-mileage cars. Typical UK cost £50–£480.
• P0089 — Fuel pressure regulator performance on VW — N276 high-pressure regulator fault on TSI and TDI. Typical UK cost £140–£4500.
• P0507 — Idle speed above expected range on VW — vacuum leak (PCV, intake manifold gasket) is the headline cause. Typical UK cost £80–£480.
• P0410 — Secondary air injection on VW — 1.4 TSI EA111 SAI pump motor seizure is the headline UK failure. Typical UK cost £180–£900.
• P0340 — Camshaft position sensor on VAG — Hall sensor failure on 1.4/1.6 FSI and 2.0 TDI common rail. Typical UK cost £65–£280.
• P0480 — Cooling fan 1 control circuit on VAG — fan control module (J293) failure on Golf/Passat/A3/Octavia. Typical UK cost £140–£420.
• P0263 — Cylinder 1 contribution/balance fault on VAG diesel — injector wear on 1.9/2.0 TDI PD and CR engines. Typical UK cost £220–£1800.
• P0430 — Bank 2 cat efficiency on VAG V6 — 3.0 TFSI supercharged and 2.0 TDI BiTDI rear O2 sensor or upstream coolant ingestion. Typical UK cost £260–£2400.
• P0234 — Turbo overboost on VAG — EA888 N75 solenoid and 1.4/1.6 TDI EA189 actuator stuck closed. Typical UK cost £140–£850.
• P0193 — Fuel rail pressure sensor high on VAG — 1.4/2.0 TSI and 2.0 TDI rail sensor false-high reading. Typical UK cost £140–£360.
• P0030 — Upstream O2 heater fault on VAG petrol — usually the four-pin connector at the sensor, not the ECU driver. Typical UK cost £70–£260.
• P0036 — Post-cat lambda heater circuit fault on VW petrol — usually sensor itself on high-mileage EA888. Typical UK cost £80–£250.
• P0402 — EGR flow excessive on VAG TDI — carbon-locked EGR valve or failing EGR position sensor. Typical UK cost £250–£950.
• P0130 — Bank 1 sensor 1 circuit fault on VW petrol — sensor response failure or connector damage on EA888. Typical UK cost £120–£340.
• P242F — DPF ash mass limit on VAG TDI — end-of-life DPF, particularly on urban EA189 cars. Typical UK cost £750–£2200.
• P0421 — Warm-up cat efficiency low on VW petrol — sensor drift or manifold cat substrate failure on EA888. Typical UK cost £250–£1400.

Codes are generic across manufacturers, but the fix is not. The same code on a Volkswagen usually points at a different component than it would on another make, which is why a make-specific diagnosis saves money before any parts are bought.