Starting, battery and electrics
Car will not start with a new battery: what it could be
If you replaced the battery and the car still will not start, the usual suspects are a poor contact at the terminals or a ground, a new battery that was not charged or a fault that was never the battery: the starter, the immobilizer or the alternator. Some cars also need the new battery registered.
Check without hurryStarting, battery and electrics
Reviewed by Daniel Morales, founder of Reprorace SL, on
Is it serious? Can I keep driving?
Usually not urgent, but do not ignore it. It is not dangerous, but do not crank the engine many times in a row: you can damage the starter or drain the battery again. If you smell burning or a cable gets hot, disconnect and call for help.
A careful, general answer: only someone who inspects the car can say whether it is safe to drive. When in doubt, stop somewhere safe and call for assistance.
Most likely causes
- Loose or corroded terminals: the contact fails even with a good battery.
- Engine or body ground: a corroded ground strap stops the starting current from flowing.
- New battery discharged or the wrong type: a different technology or capacity from what the car needs.
- Starter motor or relay: you hear a click but the engine does not turn.
- Immobilizer or key: the engine cranks but will not start, or starts and dies.
Listed from more to less common in general; on your car they may be different. A fault-code reading and a check at the garage confirm which one it is.
To understand it better: What happens if I disconnect the battery: are the codes erased? How can you tell if the 12 V battery is failing? What do the crankshaft and camshaft sensors do and what happens when they fail?
Car system: Electrical system and battery
What you can check yourself
Make sure the terminals are tight, clean and on the right polarity.
Notice whether the engine cranks or not: if it cranks but will not start, the battery is not the problem.
Measure the resting battery voltage if you have a multimeter.
Check that the battery is the type the car needs (for example AGM or EFB on cars with start-stop).
Safe checks only: with the engine off and cold whenever you look under the hood, without taking anything apart and without touching hot or moving parts.
Related fault codes
- P0562System voltage: too low
- P0563System voltage: too high
- U3003Battery voltage: malfunction
- P0335Crankshaft position sensor A, circuit: malfunction
- P0513Incorrect immobilizer key: malfunction
Generic codes that often come with this symptom. Seeing one does not confirm the cause: it is where the diagnosis starts.
How the ECO-LITE helps diagnose it
Plugged into the OBD socket, the ECO-LITE reads the fault codes of the control units that answer, with the freeze-frame data captured when the fault happened, and shows live data on your phone or computer. With your permission, your garage can see them remotely before you bring the car in.
What to look at here: resting and cranking battery voltage, low-voltage or immobilizer codes, and the engine speed signal while cranking.
Frequently asked questions
Does the new battery need registering?
On many cars with start-stop or battery management, yes: that way the system charges the new one correctly. It is done with a diagnostic tool.
Can the new battery be faulty?
It can arrive discharged or defective. Measure it or have it tested.
Why do warning lights come on after a battery change?
Some control units lose their settings or store low-voltage codes. They are read and cleared after checking.
Keep reading
- Electrical system and battery: how it works and what fails
- Car will not start and does nothing or just clicks
- Key or immobilizer light: the car does not recognize the key
- Engine cranks but will not start: causes and what to do
- Car symptoms: what they mean and what to do
- Check engine light on: what to do
- How to read and clear your car's fault codes
- OBD fault codes: what each one means