Is it safe to drive with a P0603 code?

Severity is high. Address P0603 sooner rather than later — driving with an active check engine light can worsen the problem or void emissions warranties.

How much does it cost to fix P0603?

Repair costs for P0603 typically range from $150 to $1500 in the US, depending on the underlying cause. The most common fix is: ECM internal fault.

What are the symptoms of P0603?

CEL. Fuel trims reset every drive. Slight drivability issues.

Check Engine Code

P0603

Internal Control Module KAM Error

Severity: high DIY difficulty: 5/5 Typical cost: $150–$1500

What P0603 means

Keep-Alive Memory (KAM) holds learned values like fuel trims and throttle adaptation. P0603 means the ECM can't store/retrieve from KAM correctly.

Symptoms

CEL
Fuel trims reset every drive
Slight drivability issues

Likely causes (most common first)

ECM internal fault
Battery voltage issues
Recent battery disconnection

Can I keep driving?

High — risk of damage if ignored

Typical repair cost

DIY fixes can start near $150 (parts only). Shop repairs for P0603 typically run up to $1500 depending on the underlying cause and vehicle. Start with the most common cause — ECM internal fault — before throwing parts at it.

Related codes

P0601P0604P0606

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