Powertrain, generic · Computer and auxiliary outputs

P0603 Internal Control Module Keep Alive Memory (KAM) Error

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

Keep alive memory holds learned values – fuel trim, idle and shift adaptation, readiness status – while the engine is off, as long as the module has constant battery power; CARB defines it as memory that is lost when the battery or fuse is disconnected. The module stores a checksum of this memory at shutdown and compares it at the next start (Ford, GM Europe); GM calls the check 'long term memory reset', and the Ford diesel watches the supply of its engine-off timer chip (below 0.25 V). By far the most common trigger is outside the module: a disconnected, flat or replaced battery or an interrupted constant feed – Nissan bulletins name exactly this and ask for at least 11 V before clearing. Learned values then start from default and the readiness monitors are reset. Whether the lamp comes on depends on the maker.

Likely causes

Battery disconnected, deeply discharged or replaced
Interrupted constant power feed to the module (fuse, wire, corrosion)
Main relay drops out too early, memory not saved completely at shutdown
Internal memory defect (EEPROM/NVM)

Symptoms

  • Check engine light on (depending on the maker)
  • Rough idle or changed shifting until values are relearned
  • Readiness monitors reset
  • Often right after battery work

Repair estimate

DifficultyEasyDIY possible
Parts and labour€0–1,200
Time0.2–2 h

Typical range across vehicles; the real cost depends on what the testing finds.

What to check first

  1. Check battery and grounds
  2. Clear and see if it returns
  3. Check for updates

Parts involved

engine control modulebatterycontrol module power supply

Related codes

P0562P0560P062FP068AP06B8P0604

References: law.cornell.edu, static.nhtsa.gov, static.nhtsa.gov, newtonnet.co.uk.