Skip to content
GTECH Calibration
Portal

P0603

Internal Control Module Keep Alive Memory (KAM) Error.

  • Generic
  • Powertrain
  • Generic code
  • Medium severity

How this code is built

P
SystemPowertrain
0
Defined bySAE, the same on every car
6
AreaComputer and output circuits
03
FaultThe specific fault in that area

What it means

P0603 is the generic code for an error in the Keep Alive Memory (KAM) of the engine or powertrain control module. The KAM stores learned values such as fuel trims, idle adaptations and other adaptive data, and it needs a constant supply even with the ignition off. The module sets the code when its internal self-check finds the memory unreadable, corrupted or failing to retain data, often after power has been lost or interrupted.

Symptoms

  • Engine warning light on
  • Rough or unstable idle after a battery disconnection
  • Hesitation or poor drivability while the module relearns
  • Hard starting or long cranking
  • Fuel economy worse than usual
  • Code returns soon after being cleared

Possible causes

  • Low or interrupted battery voltage, including a weak or recently disconnected batterylikely
  • Poor battery terminal connections or corroded power and earth cableslikely
  • Faulty or open circuit in the constant (permanent) power supply or earth to the control modulepossible
  • Charging system fault causing voltage spikes or dropspossible
  • Water ingress or corrosion in the module connector or module housingpossible
  • Internal failure of the control module memoryrare
  • Outdated or faulty module software where the manufacturer has issued a fix for this faultrare

How to diagnose

  1. Read all stored codes and freeze frame data, noting any other voltage or communication codes, then record and clear P0603 to see if it returns
  2. Check whether the battery was recently disconnected, replaced or jump-started, as this can set the code once
  3. Test battery condition and resting voltage, then check charging voltage with the engine running
  4. Inspect battery terminals, earth straps and main power cables for looseness, corrosion or damage
  5. Check the control module connectors for water, corrosion, bent or pushed-back pins
  6. Using the wiring diagram for the model, check the module's constant power feed, ignition feed and earth connections for voltage drop
  7. Check for relevant technical service bulletins or software updates for the vehicle and engine
  8. If power, earths and wiring are all good and the code keeps returning, test or replace the module as the manufacturer procedure directs

How to fix

  • Charge or replace a weak battery, then clear the code and complete a drive cycle so the module can relearn
  • Clean and tighten battery terminals and repair or replace damaged earth and power cables
  • Repair wiring faults or high resistance in the module's constant power and earth circuits
  • Repair any charging system fault found, such as a failing alternator or regulator
  • Dry out, clean or replace corroded connectors and fix the source of water ingress
  • Replace and programme the control module, or apply a manufacturer software update, only after other causes are ruled out

Can I keep driving?

Medium severity

The car can usually be driven short-term if it runs normally, but have it checked soon as the fault may recur and affect drivability. Avoid long journeys if it stalls, starts badly or runs poorly.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.

This code for other makes

Nearby codes