Internal Control Module Knock Control Circuit
2000-2004 Porsche Boxster 2.7L H6
Description
The ECU detected an internal fault in its knock control processing circuit. The knock sensor input is not being properly processed by the ECU, compromising engine knock protection.
Symptoms
- Check Engine Light
- Engine may run with reduced power
- Possible engine knock under load
- Safety timing retard applied
Common Causes
- ECU internal knock processing circuit failure
- Knock sensor wiring interference
- Poor ECU ground connection
- Electrical noise from aftermarket components
- ECU damage from voltage spike
Diagnostic Steps
- Check knock sensor wiring for electromagnetic interference
- Inspect ECU ground connections
- Remove aftermarket electrical components temporarily
- Test knock sensor signal quality
- Consider ECU replacement if fault is internal
Repair Notes
Address external interference sources first; replace ECU if internal circuit has failed.
Related Codes
Other Powertrain Codes
- P0001Fuel Volume Regulator Control Circuit/Open
- P0002Fuel Volume Regulator Control Circuit Range/Performance
- P0003Fuel Volume Regulator Control Circuit Low
- P0004Fuel Volume Regulator Control Circuit High
- P0010Intake Camshaft Position Actuator Circuit/Open Bank 1
- P0011Intake Camshaft Position Timing Over-Advanced Bank 1
- P0012Intake Camshaft Position Timing Over-Retarded Bank 1
- P0013Exhaust Camshaft Position Actuator Circuit/Open Bank 1
- P0014Exhaust Camshaft Position Timing Over-Advanced Bank 1
- P0015Exhaust Camshaft Position Timing Over-Retarded Bank 1
P1388 on Other Vehicles
Porsche 718 Boxster
2017-2024 2.0L H4 Turbo
Porsche 718 Boxster
2017-2024 2.0L Turbo H4
Porsche 718 Boxster GTS
2020-2024 4.0L H6
Porsche 718 Boxster S
2017-2024 2.5L Turbo H4
Porsche 718 Cayman
2017-2024 2.0L H4 Turbo
Porsche 718 Cayman
2017-2024 2.0L Turbo H4
Porsche 718 Cayman GT4
2019-2024 4.0L H6
Porsche 718 Cayman GTS
2020-2024 4.0L H6
Common Questions
What does code P1388 mean on a 2000-2004 Porsche Boxster?
P1388 stands for "Internal Control Module Knock Control Circuit". The ECU detected an internal fault in its knock control processing circuit. The knock sensor input is not being properly processed by the ECU, compromising engine knock protection.
What are the symptoms of P1388 on a Porsche Boxster?
Common symptoms of P1388 include: Check Engine Light, Engine may run with reduced power, Possible engine knock under load, Safety timing retard applied.
What causes P1388 on a 2000-2004 Porsche Boxster?
Common causes of P1388 include: ECU internal knock processing circuit failure, Knock sensor wiring interference, Poor ECU ground connection, Electrical noise from aftermarket components, ECU damage from voltage spike.