P1602high severityPowertrain
Power Supply Voltage Too Low
on 2021 Audi A3 2.0L Turbo I4 · AWD
What this code means
The ECU detected that its supply voltage has dropped below the minimum operating threshold. Low voltage can cause erratic ECU behavior, false fault codes, and poor engine performance.
Symptoms
- Check Engine Light
- Multiple fault codes stored
- Engine running rough
- Starting difficulties
- Electrical accessories dimming
Common causes
- Weak or failing battery
- Faulty alternator or voltage regulator
- Corroded battery terminals
- High-resistance connection in power supply
- Parasitic drain depleting battery
Diagnostic steps
- Test battery voltage and load test
- Test alternator output voltage and current
- Inspect battery terminals and connections
- Check main power supply wiring to ECU
- Test for parasitic electrical drain
Repair notes
Replace the battery or alternator; clean and tighten all power supply connections.
Other Powertrain codes on this vehicle
P0001
Fuel Volume Regulator Control Circuit/Open
P0002
Fuel Volume Regulator Control Circuit Range/Performance
P0003
Fuel Volume Regulator Control Circuit Low
P0004
Fuel Volume Regulator Control Circuit High
P0010
Intake Camshaft Position Actuator Circuit/Open Bank 1
P0011
Intake Camshaft Position Timing Over-Advanced Bank 1
P0012
Intake Camshaft Position Timing Over-Retarded Bank 1
P0013
Exhaust Camshaft Position Actuator Circuit/Open Bank 1
P0014
Exhaust Camshaft Position Timing Over-Advanced Bank 1
P0015
Exhaust Camshaft Position Timing Over-Retarded Bank 1