What usually causes it
- A battery that was disconnected, replaced or went dead
- Loose or rusty battery cables
- A bad ground wire
- A failing engine computer
P0603Starts at: OK to drive, fix when convenient
Engine computer lost its saved settings
The engine computer keeps some settings in memory that stays alive when the car is off. It lost or damaged that memory, often because the power was cut.
Check this first
Make sure the battery cables are tight and clean. If the battery was just disconnected, drive normally for a few days and see if the code comes back.
What to watch for
- The code coming back after a few days
- Hard starting or a rough idle
- Other warning lights coming on
Can I keep driving?
We rate P0603 as OK to drive, fix when convenient, as a starting point. Keep an eye on the signs below. If the light starts flashing, stop driving soon.
Quick answers about P0603
What does P0603 mean?
Engine computer lost its saved settings. The engine computer keeps some settings in memory that stays alive when the car is off. It lost or damaged that memory, often because the power was cut.
Can I keep driving with P0603?
We rate P0603 as OK to drive, fix when convenient, as a starting point. Keep an eye on the signs below. If the light starts flashing, stop driving soon.
What usually causes P0603?
The most common causes, in order: A battery that was disconnected, replaced or went dead; Loose or rusty battery cables; A bad ground wire; A failing engine computer.
Estimates only. A mechanic should confirm. The same code can mean slightly different things on different cars; the app explains it for your exact year, make, model and mileage.