Skip to content

Car Symptoms Guide

Identify car problems by their symptoms. Learn what common warning signs mean and find related OBD-II trouble codes.

Check Engine Light

Moderate

The check engine light (CEL) or malfunction indicator lamp (MIL) illuminates on your dashboard.

P0420P0300P0171P0442+3 more

Rough Idle

Moderate

Your engine shakes, vibrates, or runs unevenly when the vehicle is stopped.

P0300P0301P0302P0303+4 more

Poor Fuel Economy

Low

Your vehicle is using more fuel than normal for the same driving conditions.

P0171P0172P0174P0101+3 more

Engine Misfires

High

The engine stumbles, hesitates, or jerks during acceleration.

P0300P0301P0302P0303+3 more

Car Won't Start

Critical

The engine cranks but won't turn over, or nothing happens when you turn the key.

P0335P0340P0230P0562

Engine Overheating

Critical

The temperature gauge reads high, steam from the hood, or an overheating warning light appears.

P0217P0117P0116

Strange Exhaust Smell

Moderate

Unusual odors coming from the exhaust, such as rotten eggs, sweet smell, or burning oil.

P0420P0430P0171P0172

Transmission Slipping

High

The transmission hesitates, slips between gears, or shifts unexpectedly.

P0700P0730P0740P0715

Loss of Power

Moderate

The vehicle feels sluggish, has reduced acceleration, or lacks its normal power.

P0101P0171P0300P0420+1 more

Gas Smell in Cabin

High

You can smell gasoline inside the vehicle or near the exterior.

P0440P0442P0446P0449+3 more

Squealing or Grinding Brakes

High

High-pitched squealing, grinding, or scraping sounds when applying the brakes.

Steering Wheel Vibration

Moderate

The steering wheel shakes or vibrates at certain speeds or when braking.

Oil Pressure Warning Light

Critical

The oil pressure warning light illuminates on the dashboard.

P0520

Battery/Charging Warning Light

High

The battery or charging system warning light appears on the dashboard.

P0562

White Exhaust Smoke

Critical

Thick white smoke or steam coming from the exhaust pipe.

P0128P0117