B1006 — Replace Electronic Control Unit (ECU)

Causes

• Internal ECU hardware failure (processor, memory, PCB damage)
• Corrosion or water ingress into the ECU housing or connector
• Severe electrical event: short circuit, over-voltage, or reverse polarity
• Failed CAN/LIN transceiver or other internal communication interface
• Corrupted or failed firmware/flash memory
• Damaged connector pins, poor ground or power supply

Symptoms

• Malfunction indicator lights (MIL) or multiple warning lamps illuminated
• Loss of communication with the module on a diagnostic scan tool (Uxxxx codes)
• One or more vehicle systems controlled by this ECU not operating or operating intermittently
• Reduced functionality of vehicle features (e.g., immobilizer, central locking, lighting, instruments)
• Vehicle may enter limp mode or refuse to start if ECU is critical to engine management

What to check

• Read all stored and pending DTCs from all control modules and record freeze frame/verification data
• Look for related communication codes (U-codes) that indicate bus or gateway issues
• Visually inspect ECU housing and connectors for corrosion, water ingress, burn marks or melted plastic
• Check fuses and fusible links supplying the ECU
• Measure supply voltage at the ECU connector with ignition ON (see signal parameters)
• Verify good engine/chassis grounds and continuity to battery negative

Signal parameters

• Primary supply voltage: ~11–14 V with ignition ON; should be near battery voltage
• Sleep/standby current: small (vehicle dependent) — unusual high current may indicate fault
• CAN bus voltages (typical): CAN_H ≈ 2.5 V idle, CAN_L ≈ 2.5 V idle; differential ≈0 V recessive, ≈2 V dominant — verify steady signals and activity during communication
• LIN bus: idle near battery voltage on the line when inactive (vehicle dependent)
• Ground resistance: close to 0 Ω to chassis (low milliohms preferred)

Similar codes