P0603: Internal Control Module Keep Alive Memory (KAM) Error
The engine computer has found a problem with the memory that saves its learned settings while the car is off.
What P0603 means
Keep alive memory, or KAM, is where the engine computer stores what it has learned while driving: fuel trims, idle settings and on many cars transmission shift adaptations. It needs a constant 12 volt feed to hold those values when the key is off. RepairPal explains that P0603 means the KAM self test is failing. Very often, the cause is simple: the battery was disconnected, went dead or has a poor connection, so the memory was wiped. A blown fuse in the constant power circuit or a bad ground can cause the same thing every time the car sits. Less often, the computer itself has failed. KBB notes you can usually drive to a shop, though driving quality may drop because the learned settings keep getting reset. Shops check battery condition and terminals, measure the constant power feed to the computer with the key off and test grounds. They only replace the computer after confirming power and ground are good.
Common symptoms
- Check engine light on
- Rough idle after every start
- Poor fuel economy
- Shifting that feels off
- Code returns after every battery disconnect
Most common causes
- Recently disconnected or dead battery
- Weak battery or poor battery connections
- Blown keep alive memory fuse
- Bad constant power feed or ground to the computer
- Failed engine computer
What to check yourself first
If the battery was recently disconnected or died, clear the code and drive normally for a few days to see whether it returns. Clean and tighten the battery terminals. Check the fuse that supplies constant power to the engine computer.
Typical fixes and what they cost
| Fix | Typical cost | Note |
|---|---|---|
| Replace battery | $456-$493 | A weak or recently replaced battery is a common trigger. |
| Electrical diagnosis to find a wiring or connector fault | $122-$179 | Tests the constant power feed, fuses and grounds to the computer. |
| Replace engine control module (ECM/PCM) | $1,122-$1,192 | Only if power and grounds are good and the error keeps returning. |
Typical US price ranges for parts and labor, not quotes. Your shop should confirm the cause with a diagnostic before replacing parts.
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Related codes
- P0601 Internal Control Module Memory Check Sum Error
- P0604 Internal Control Module Random Access Memory (RAM) Error
- P0606 Control Module Processor
- P0562 System Voltage Low
- P0505 Idle Air Control System