Find What’s Wrong With Your Car.
Trouble codes, warning lights, symptoms and troubleshooting guides for everyday car problems.
Search by Problem
You don’t need to know the name of the part. Start with what you can see, hear, smell or feel — we’ll work back to the likely cause.
Popular Trouble Codes
All trouble codes ›Plugged in a scanner and got a code? Here’s what it actually means, how serious it is and what usually fixes it.
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P0351 Code: Ignition Coil A Primary/Secondary Circuit
P0351 means the engine computer saw a fault in ignition coil A’s circuit: usually a loose connector, chafed wire or failed $40-$150…
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P2135 Code: Throttle Position Sensor A/B Voltage Correlation
P2135 means the two throttle position sensor signals disagree, so the engine cuts power. Usual causes: worn sensor or bad connector, $0-$800…
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P0606 Code: Control Module Processor Fault (ECM/PCM)
P0606 means the engine computer failed its own processor self-test. Check battery voltage (12.6 V at rest) and grounds before replacing the…
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P0457 Code: EVAP Leak Detected (Fuel Cap Loose/Off)
P0457 means the EVAP leak test failed soon after refuelling, so the fuel cap is the prime suspect. Causes, fixes from $0,…
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P0730 Code: Incorrect Gear Ratio (Causes and Fixes)
P0730 means the transmission’s measured gear ratio doesn’t match the commanded gear. Causes, diagnosis and repair costs from $20 to $6,000.
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P0118 Code: Engine Coolant Temperature Sensor Circuit High
P0118 means the coolant temperature sensor circuit reads high voltage (often -40°F): usually an open wire or failed $20-$60 sensor, not a…
Dashboard Warning Lights
All warning lights ›Amber means investigate soon. Red means stop safely and check now. Tap a light to see what triggers it and whether you can keep driving.
Common Car Problems
All problems ›-
Windshield Wipers Stop Working or Move Slowly
When wipers won’t move or crawl across the glass, check the fuse, then the motor and linkage. This is a different fault…
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Headlights Dim or Flicker While Driving
Headlights that dim at idle or flicker as you drive usually point to the charging system or a poor connection, not the…
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AC Blows Cold Only While Driving, Warm at Idle
An AC that cools well at speed but warms up when you stop is usually short of airflow across the condenser —…
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Car Heater Blows Cold Air
A car heater runs on engine coolant, so cold air from the vents usually means low coolant, an engine that isn’t warming…
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Car Windows Fog Up Inside and Won’t Clear
Inside fogging means moisture in the cabin that the climate system isn’t clearing. Check the simple settings first — and know when…
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Power Steering Whine When Turning the Wheel
A whining or moaning noise that rises as you turn the steering wheel points to the power steering pump — and low…
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Browse by Car Brand
All brands ›Every make has its known weak points. Find the faults, codes and warning lights that owners of your car report most.
Latest Troubleshooting Guides
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P2135 Code: Throttle Position Sensor A/B Voltage Correlation
P2135 means the two throttle position sensor signals disagree, so the engine cuts power. Usual causes: worn sensor or bad connector, $0-$800…
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P0351 Code: Ignition Coil A Primary/Secondary Circuit
P0351 means the engine computer saw a fault in ignition coil A’s circuit: usually a loose connector, chafed wire or failed $40-$150…
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P0606 Code: Control Module Processor Fault (ECM/PCM)
P0606 means the engine computer failed its own processor self-test. Check battery voltage (12.6 V at rest) and grounds before replacing the…
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Honda Odyssey Common Problems: 9-Speed, P0716 & Doors
Honda Odyssey common problems: 2018-2019 9-speed harsh shifts and P0716 (bulletin 19-124), sliding door and seat recalls, VCM and timing belt.
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Mini Cooper R56 Common Problems: Timing Chain and More
Mini Cooper R56 common problems: N14 timing chain wear on 2007-2010 Cooper S, coolant leaks, oil use and the water pump fire…
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P0457 Code: EVAP Leak Detected (Fuel Cap Loose/Off)
P0457 means the EVAP leak test failed soon after refuelling, so the fuel cap is the prime suspect. Causes, fixes from $0,…
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P0118 Code: Engine Coolant Temperature Sensor Circuit High
P0118 means the coolant temperature sensor circuit reads high voltage (often -40°F): usually an open wire or failed $20-$60 sensor, not a…
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P0730 Code: Incorrect Gear Ratio (Causes and Fixes)
P0730 means the transmission’s measured gear ratio doesn’t match the commanded gear. Causes, diagnosis and repair costs from $20 to $6,000.