P0420: catalyst efficiency
P0420 means the Bank 1 catalyst failed an efficiency check. Learn how exhaust leaks, sensor response, and engine problems affect the repair decision.
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P0300: random misfire
P0300 means the engine detected a misfire pattern. Learn what to do if the light flashes and how cylinder data and driving conditions narrow the cause.
P0171: a lean-running engine
Understand P0171, how fuel trims reveal a lean pattern, and why checking for unmetered air can be more useful than replacing an oxygen sensor.
A flashing check engine light
A flashing check engine light while driving can signal a damaging misfire. Know what to do if the car shakes, loses power, or the flashing stops.
When your car won’t crank
If the lights come on but the engine won't turn over, use the sound, dash behavior, and jump-start result to narrow down the next check.
AC blowing warm air
Narrow down a car AC problem by comparing airflow, cooling at idle, and driver versus passenger vents. Learn what to check before paying for a recharge.
Why your car is overheating
What to do when your engine overheats, why a full coolant reservoir can be misleading, and how traffic, highway driving, and AC use guide diagnosis.
Tracing an engine oil leak
Learn what an oil spot under a parked car can tell you, what to do after an oil change, and why the source of the leak matters more than the puddle size.
Alternator replacement cost
RepairPal puts US alternator replacement at $809–$1,088. See the parts and labor breakdown, what the estimate excludes, and how to compare local quotes.
Starter replacement cost
US starter replacement averages $565–$796 in RepairPal's estimate. Learn how vehicle access, starter fit, diagnosis, and scheduling affect your quote.
Brake pad & rotor replacement cost
Compare US brake pad and rotor cost estimates, see what changes the price for each axle, and learn which measurements justify replacing the rotors.
Transmission repair & replacement
Compare a US transmission replacement estimate with the work covered by a repair, rebuild, or exchange unit. See how labor, downtime, and terms affect the choice.
Suspension clunks & squeaks
Use the location, timing, and feel of a suspension noise to narrow the inspection. Learn which steering changes make a clunk or squeak urgent.
Blown head gasket symptoms
Learn which combinations of coolant loss, white exhaust, and rough running suggest a head gasket leak, what can mimic it, and when to stop driving.
A battery that drains overnight
Tell parked battery drain from weak battery capacity, poor connections, or undercharging. Learn how shops measure key-off current and trace intermittent loads.
Bad spark plug symptoms
Learn how worn or fouled spark plugs affect starting, idle, and acceleration, what the firing end can reveal, and how a shop separates plug and coil faults.
Wheel bearing or tire noise?
A hum that builds with road speed can come from a wheel bearing or a tire. Learn what turns, pavement changes, and a wheel inspection can reveal.
Fuel pump replacement cost
Compare the US fuel pump replacement estimate of $1,344–$1,513 with an itemized shop quote, including pump type, tank access, diagnosis, and pickup time.
Catalytic converter replacement cost
See the $2,280–$2,480 US catalytic converter replacement estimate and how the assembly, labor, emissions approval, and possible warranty coverage affect your bill.
How long do brake pads last?
Learn why brake pad mileage varies, how to use front and rear pad measurements, and which changes in noise, pedal feel, or stopping power need attention.
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