Plain English explanations · VAG specific notes · India, UK and US repair costs
Fault code explanations are written from real car ownership experience and OBD2 diagnostics. Repair costs shown are estimated ranges based on typical market rates in India, UK and US — actual costs vary depending on your location, vehicle model, and garage. Always get a quote before authorising any repair.
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OBD2 Fault Code Lookup Tool — 34 Common Codes Explained
This tool covers the most common OBD2 fault codes with plain English explanations, safe to drive ratings, VAG specific notes for VW, Skoda, Audi and SEAT vehicles, and repair costs for India, UK and US.
P0171 system too lean bank 1 — vacuum leak dirty MAF sensor weak fuel pressure — safe to drive carefully — repair cost India rupees 800 to 8000 UK pounds 60 to 350
P0300 random multiple cylinder misfire — worn spark plugs failing ignition coils — do not drive — repair cost India rupees 1500 to 12000 UK pounds 80 to 600
P0420 catalyst system efficiency below threshold — failing catalytic converter faulty downstream O2 sensor — safe to drive — repair cost India rupees 4000 to 25000 UK pounds 80 to 900
P0128 coolant temperature below thermostat regulating temperature — thermostat stuck open — safe to drive — repair cost India rupees 1500 to 8000 UK pounds 60 to 250
P0217 engine coolant over temperature — stop driving immediately — low coolant cooling fan failure blown head gasket
P0087 fuel rail pressure too low — clogged fuel filter weak fuel pump — drive carefully — repair cost India rupees 500 to 35000 UK pounds 30 to 1200
P0102 MAF sensor circuit low input — dirty MAF sensor — safe to drive — repair cost India rupees 300 to 8000 UK pounds 8 to 250
P0131 O2 sensor low voltage bank 1 sensor 1 — failing upstream oxygen sensor exhaust leak — safe to drive
P0132 O2 sensor high voltage bank 1 sensor 1 — failing upstream oxygen sensor engine running rich — safe to drive
P0133 O2 sensor slow response bank 1 sensor 1 — aging oxygen sensor — safe to drive
P0134 O2 sensor no activity bank 1 sensor 1 — failed upstream oxygen sensor — safe to drive carefully
P0136 O2 sensor circuit malfunction bank 1 sensor 2 — faulty downstream oxygen sensor — safe to drive
P0141 O2 sensor heater circuit bank 1 sensor 2 — failed heater element check fuse first — safe to drive
P0172 system too rich bank 1 — leaking fuel injector faulty O2 sensor — safe to drive carefully
P0299 turbocharger underboost condition — boost leak cracked intercooler hose — drive carefully — repair cost India rupees 500 to 40000 UK pounds 30 to 2000
P0234 turbocharger overboost condition — stuck wastegate N75 solenoid fault — drive carefully avoid full throttle
P0301 cylinder 1 misfire detected — faulty spark plug ignition coil — drive gently
P0302 cylinder 2 misfire detected — faulty spark plug ignition coil — drive gently
P0303 cylinder 3 misfire detected — faulty spark plug ignition coil — drive gently
P0304 cylinder 4 misfire detected — faulty spark plug ignition coil — drive gently
P0335 crankshaft position sensor circuit malfunction — do not drive risk of sudden stall
P0340 camshaft position sensor circuit malfunction — do not drive risk of sudden stall
P0011 camshaft timing over advanced bank 1 — low oil level degraded oil VVT solenoid — check oil first
P0016 crankshaft camshaft position correlation — do not drive potential timing chain fault
P0401 EGR flow insufficient — carbon buildup EGR valve — very common on diesel engines — safe to drive
P0440 evaporative emission system malfunction — loose fuel filler cap EVAP purge valve — safe to drive
P0505 idle air control system malfunction — dirty throttle body vacuum leak — safe to drive
P0507 idle RPM higher than expected — vacuum leak — safe to drive
P0562 system voltage low — failing battery faulty alternator — drive carefully — causes multiple false fault codes
P0670 glow plug control module circuit fault — diesel engine cold start issue — safe to drive once started
P0700 transmission control system malfunction — read all transmission codes — drive carefully
P0741 torque converter clutch circuit — degraded transmission fluid — safe to drive avoid long motorway journeys
P2002 diesel particulate filter efficiency below threshold — blocked DPF short journeys — drive carefully
P2459 diesel particulate filter regeneration frequency — EGR fault causing excessive soot — safe to drive investigate root cause