Car Won't Start but Has Power -- Common Codes and Causes

Has Power but Won't Start: Narrowing It Down

When your car has power (dashboard lights work, radio turns on) but the engine won't start, the battery usually isn't the problem. The issue is almost always in one of three systems: ignition (the spark that ignites fuel), fuel delivery (getting gas to the engine), or the sensors that tell the computer when to fire. If the engine cranks (you hear the starter motor spinning) but won't fire up, that's different from turning the key and hearing nothing or just a click. Cranks-but-won't-start is a fuel or spark issue. No-crank is a starter or electrical issue. Knowing which one you have helps you find the right codes.

Crank Sensor Failure: Code P0335

The crankshaft position sensor tells your car's computer exactly where the engine is in its rotation cycle. Without this signal, the computer doesn't know when to fire the spark plugs or fuel injectors, so it simply won't start the engine. Code P0335 means the crankshaft position sensor circuit has no signal. This is one of the most common reasons for a sudden no-start condition where the engine cranks but refuses to fire. The sensor itself costs $20 to $75, and replacement is usually a one-hour job. On many vehicles, it's located near the bottom of the engine near the crankshaft pulley.

Camshaft Sensor Issues: Code P0340

The camshaft position sensor works with the crankshaft sensor to time the engine's fuel injection and ignition. Code P0340 means the camshaft position sensor circuit is malfunctioning. While some cars can still run with a bad cam sensor by relying on the crank sensor alone, many modern vehicles will not start at all without a cam sensor signal. Symptoms before a complete failure often include rough running, hesitation, or stalling. If your car was running rough for a few days before it stopped starting, a failing cam sensor is a strong suspect. Replacement costs are similar to the crank sensor, typically $30 to $100 for the part.

Fuel Pump Problems: Code P0230

If you turn the key to the on position (without cranking) and don't hear a brief humming sound from the rear of the car, your fuel pump may not be running. Code P0230 relates to the fuel pump primary circuit. Without fuel pressure, the engine will crank but never start. Before assuming the pump is dead, check the fuel pump fuse and relay first. These are located in the fuse box, usually under the hood or under the dashboard. A blown fuse is a $2 fix. The relay is about $15. If those are fine and you're getting no fuel pressure, the pump itself may need replacement, which typically costs $400 to $800 including labor.

What to Do When Your Car Won't Start

Here's a quick diagnostic checklist. First, turn the key to the on position without cranking and listen for the fuel pump hum from the back of the car. No hum could mean a fuel pump, fuse, or relay issue. Second, try cranking. If it cranks strong but won't fire, the battery and starter are fine, and you're looking at fuel or spark problems. Third, if you have an OBD-II scanner, plug it in with the key in the on position. Many scanners can read codes even when the engine won't start. Look for codes like P0335, P0340, or P0230. Fourth, check for obvious things: is there gas in the tank, did the security light come on (anti-theft systems can prevent starting), and is the key fob battery dead on push-button-start vehicles?

Frequently Asked Questions