Something wrong with your car? Find the part
Pick the problem or type the error code from a scan. You'll see the parts that usually cause it, with fair prices, and can get a quote from verified dealers in seconds.
Pick what your car is doing, or type the error code from a scan.
Common problems and their usual causes
Check engine light keeps coming on
Usually a sensor. A quick scan (OBD) at any garage gives an error code like P0171. Send us the code and we'll tell you the exact part. These are the most common causes:
Engine overheating
Stop driving when the gauge is high: it can damage the engine. Most often it's one of these:
Car won't start
A click with dim lights is usually the battery. Turning over but not firing points to fuel or spark.
Engine shaking, misfiring or losing power
Shaking at idle or when you accelerate is most often spark or air/fuel:
Battery light on, battery keeps dying
If the battery keeps going flat, check the charging system before buying a new battery:
Squeaking or grinding when braking
Squeaking is usually worn pads; grinding or a shaking steering wheel means the discs too:
Clicking when turning
A click on full lock is almost always the outer CV joint. Fix it early: a torn boot lets dirt in.
Knocking over bumps or a bouncy ride
Knocks over bumps are usually links or bushes; a bouncy ride means shocks; a hum that grows with speed is a wheel bearing:
AC not cooling
Start with a gas check: it's the cheapest fix. If it leaks again, it's a part:
Smoke from the exhaust
Blue smoke is burning oil; white (sweet smell) is coolant; black is too much fuel:
Gears slipping or hard to change
Manual: usually the clutch. Automatic or CVT: often old fluid or a solenoid. Check the fluid first:
Loud exhaust or rattling underneath
A sudden loud exhaust is usually a hole in the silencer or pipe:
Engine error codes
A garage or a cheap OBD scanner reads these from your car. The code points to the system; a mechanic should confirm the part before you buy.
| Code | What it means | Usual parts |
|---|---|---|
| P0100 | Air flow sensor circuit | Mass Air Flow Sensor, Engine Air Filter |
| P0101 | Air flow sensor reading out of range | Mass Air Flow Sensor, Engine Air Filter |
| P0102 | Air flow sensor signal low | Mass Air Flow Sensor |
| P0106 | Manifold pressure (MAP) sensor out of range | MAP Sensor |
| P0113 | Intake air temperature sensor | Mass Air Flow Sensor |
| P0115 | Coolant temperature sensor circuit | Coolant Temperature Sensor |
| P0117 | Coolant temperature sensor low | Coolant Temperature Sensor |
| P0118 | Coolant temperature sensor high | Coolant Temperature Sensor |
| P0120 | Throttle position sensor circuit | Throttle Position Sensor |
| P0121 | Throttle position sensor out of range | Throttle Position Sensor |
| P0128 | Engine not warming up properly | Thermostat, Coolant Temperature Sensor |
| P0130 | Oxygen sensor circuit (front) | Oxygen Sensor |
| P0131 | Oxygen sensor low voltage | Oxygen Sensor |
| P0133 | Oxygen sensor slow response | Oxygen Sensor |
| P0134 | Oxygen sensor no activity | Oxygen Sensor |
| P0135 | Oxygen sensor heater (front) | Oxygen Sensor |
| P0136 | Oxygen sensor circuit (rear) | Oxygen Sensor |
| P0141 | Oxygen sensor heater (rear) | Oxygen Sensor |
| P0171 | Engine running too lean | Mass Air Flow Sensor, Oxygen Sensor, Fuel Filter, Fuel Pump, Fuel Injectors |
| P0172 | Engine running too rich | Oxygen Sensor, Mass Air Flow Sensor, Fuel Injectors |
| P0300 | Random misfire | Spark Plugs (set of 4), Ignition Coil, Spark Plug Leads, Fuel Injectors |
| P0301 | Misfire, cylinder 1 | Spark Plugs (set of 4), Ignition Coil, Fuel Injectors |
| P0302 | Misfire, cylinder 2 | Spark Plugs (set of 4), Ignition Coil, Fuel Injectors |
| P0303 | Misfire, cylinder 3 | Spark Plugs (set of 4), Ignition Coil, Fuel Injectors |
| P0304 | Misfire, cylinder 4 | Spark Plugs (set of 4), Ignition Coil, Fuel Injectors |
| P0325 | Knock sensor circuit | Knock Sensor |
| P0335 | Crankshaft position sensor | Crankshaft Position Sensor |
| P0340 | Camshaft position sensor | Camshaft Position Sensor |
| P0351 | Ignition coil circuit | Ignition Coil |
| P0400 | EGR flow problem | EGR Valve |
| P0401 | EGR flow too low | EGR Valve |
| P0420 | Catalytic converter efficiency low | Catalytic Converter, Oxygen Sensor |
| P0440 | Evaporative system leak | Fuel Cap |
| P0442 | Small evaporative leak | Fuel Cap |
| P0455 | Large evaporative leak | Fuel Cap |
| P0500 | Vehicle speed sensor | ABS Wheel Speed Sensor |
| P0505 | Idle control problem | Idle Control Valve, Throttle Position Sensor |
| P0507 | Idle speed too high | Idle Control Valve |
| P0562 | System voltage low | Alternator, Car Battery |
| P0700 | Gearbox control fault | Gearbox Solenoid, Gearbox Oil / ATF |
| P0741 | Torque converter lock-up | Gearbox Solenoid, Gearbox Oil / ATF |
| P2002 | Diesel particulate filter efficiency | Diesel Particulate Filter |
| C0035 | Front left wheel speed sensor | ABS Wheel Speed Sensor |
| C0040 | Front right wheel speed sensor | ABS Wheel Speed Sensor |