Car won't start? We come to it

"It won't start" covers a handful of very different problems, and the fix depends entirely on which one you have. The good news: a mobile mechanic can tell them apart in minutes with the car exactly where it is, and almost every cause is an on-site repair with a part that's stocked locally.

The worst move is a tow. You pay to move a car that might need a forty-dollar relay, then pay a shop to tell you that, then wait. The better move is a mobile mechanic who comes to the car, diagnoses it and fixes it, with a quote before any part is replaced.

Mobile-Mechanic.xyz has a local mechanic in 250 cities, and no-starts are the job they take first. Describe exactly what the car does when you turn the key; it tells the mechanic most of what they need to know.

Listen to the car and describe it. Each sound points somewhere:

• Rapid clicking, dim lights: the battery is flat or the terminals are bad
• One loud click, bright lights: the starter or its solenoid
• Cranks normally, never catches: fuel or spark, often the fuel pump, a relay or a crank sensor
• Started on a jump, died while driving: the alternator isn't charging
• Nothing at all, no lights: a dead battery, a bad main cable or a blown main fuse
• Cranks slowly: a weak battery, a tired starter or, in cold weather, the wrong oil

Battery first: voltage and a load test, plus a look at the terminals and cables, because corroded connections cause more no-starts than people expect. Then the starter: is it getting voltage, and is it drawing too much current? Then charging: does the alternator produce the right voltage once the car runs?

If the car cranks but doesn't fire, the test moves to fuel pressure, spark and the sensors the engine needs to start. A scan for codes often shortcuts this; a crankshaft position sensor code, for instance, explains a crank-no-start immediately. The mobile car diagnostic confirms the cause before any part is bought.

Make sure the car is in Park or Neutral, the steering lock isn't binding the key, and the key fob battery isn't dead if the car uses push-button start. Check that the battery terminals are tight and not caked in white or green corrosion. If the lights are bright and the car just clicks once, don't keep trying; repeated attempts can overheat the starter.

If the lights are dim and a neighbor can give you a jump, that will often get a car with a dead battery running. But a car that needed a jump needs the battery and alternator tested, because it will happen again. A jump start gets you moving; the test tells you why it died.

It depends on the cause, which is why the test comes first. A terminal cleaning is a small job; a battery, starter or alternator is a moderate one; a fuel pump is the larger end. Whatever it is, you get a quote before the part is replaced, there's no tow and no shop diagnostic fee. The mobile mechanic cost page explains how quotes work.

The money saved by not towing a car that needed a battery is the whole argument for mobile repair.