What does fault code P0601 mean?

The control module has detected a fault in the Internal Control Module Memory Check Sum Error (P0601). The reported signal is electrically valid but disagrees with other operating parameters (RPM, load, or other sensors). The underlying code points specifically at non-volatile memory (EEPROM/KAM). Measurements: • Internal Control Module Memory Check Sum Error – Permanent B+ Supply (Voltage (V)): 12.4 - 12.7 V (ignition OFF) / 13.5 - 14.7 V (engine running) [Condition: At module supply pins] • Internal Control Module Memory Check Sum Error – Ignition-Switched Supply (Voltage (V)): 11.8 - 14.4 V [Condition: Ignition ON] • Internal Control Module Memory Check Sum Error – Ground Connections Voltage Drop (Voltage (V)): < 0.1 V per ground point [Condition: Under load to battery negative] • Internal Control Module Memory Check Sum Error – 5 V Reference Outputs (Voltage (V)): 4.95 - 5.05 V per circuit [Condition: Ignition ON, sensors unplugged one at a time] Oscilloscope: Log module supply voltage during cranking and load changes. It must not fall below 9.5 V on start or carry high-frequency noise that disturbs the processor. (Scale: 500 ms/div, 5 V/div)

Standard EOBD

P0601 - Internal Control Module Memory Check Sum Error

Q: What causes fault code P0601?

Most likely: Lost adaptation values after a battery disconnect, or a worn EEPROM cell after many write cycles Most likely: Internal Control Module Memory Check Sum Error is electrically operational but performing outside calibrated tolerance Likely: Chafed or pinched wiring harness along the signal path to Internal Control Module Memory Check Sum Error Likely: Poor ground connection or excessive voltage drop (> 0.1 V) at the ground point for Internal Control Module Memory Check Sum Error Rare: Defective internal output driver or reference circuit in the control module for Internal Control Module Memory Check Sum Error

Related:Internal Control Module Memory Check Sum Error, Wiring harness and connectors, Control Module (ECM/PCM)

System

Powertrain (Engine & Gearbox)

Technical Description

The control module has detected a fault in the Internal Control Module Memory Check Sum Error (P0601). The reported signal is electrically valid but disagrees with other operating parameters (RPM, load, or other sensors). The underlying code points specifically at non-volatile memory (EEPROM/KAM).

Multimeter Test Points & Nominal Values

Test Point / Component	Measurement	Nominal Target Range	Test Condition
Internal Control Module Memory Check Sum Error – Permanent B+ Supply	Voltage (V)	12.4 - 12.7 V (ignition OFF) / 13.5 - 14.7 V (engine running)	At module supply pins
Internal Control Module Memory Check Sum Error – Ignition-Switched Supply	Voltage (V)	11.8 - 14.4 V	Ignition ON
Internal Control Module Memory Check Sum Error – Ground Connections Voltage Drop	Voltage (V)	< 0.1 V per ground point	Under load to battery negative
Internal Control Module Memory Check Sum Error – 5 V Reference Outputs	Voltage (V)	4.95 - 5.05 V per circuit	Ignition ON, sensors unplugged one at a time

Internal Control Module Memory Check Sum Error – Permanent B+ SupplyVoltage (V)

Nominal Target:12.4 - 12.7 V (ignition OFF) / 13.5 - 14.7 V (engine running)

At module supply pins

Internal Control Module Memory Check Sum Error – Ignition-Switched SupplyVoltage (V)

Nominal Target:11.8 - 14.4 V

Ignition ON

Internal Control Module Memory Check Sum Error – Ground Connections Voltage DropVoltage (V)

Nominal Target:< 0.1 V per ground point

Under load to battery negative

Internal Control Module Memory Check Sum Error – 5 V Reference OutputsVoltage (V)

Nominal Target:4.95 - 5.05 V per circuit

Ignition ON, sensors unplugged one at a time

Oscilloscope Waveform Analysis

500 ms/div, 5 V/div

Log module supply voltage during cranking and load changes. It must not fall below 9.5 V on start or carry high-frequency noise that disturbs the processor.