P1602 Engine computer supply (terminal 30) too low
P1602 means: Engine computer supply (terminal 30) too low. The computer monitors battery voltage and charging. Drive gently and have the car checked soon. The most common repair costs about €120–220 in Estonia, depending on make and model. The most common cause: weak or old battery.
What it means
The computer monitors battery voltage and charging. The voltage is too low, too high or unstable. A weak battery can also cause other odd faults.
This is a make-specific code (VAG). The exact meaning can vary by model and year.
What you may notice
- Hard starting
- Lights dim
- Battery light may be on
- Random warnings on the dashboard
What could be wrong
- 1Weak or old battery · Battery replacement €120–220
- 2Alternator not charging properly · Alternator replacement €350–650
- 3Battery terminals or ground strap in poor condition · Battery replacement €120–220
- 4Slipping alternator belt · Alternator replacement €350–650
- 5Something draining the battery while parked · Battery drain search €45–90
Repair difficulty: Easy
What you can check yourself
Check that the battery terminals are clean and tight. With the engine running, battery voltage should be about 13.8–14.7 V. You can do the simpler checks yourself.
How we fix it
- We load-test the battery
- We measure the alternator charging voltage
- We check grounds and current drain
- We replace the battery or repair the alternator
Standard SAE description: Power Supply (B+) Terminal 30 Low Voltage