P06D1: Ignition-control performance can be an internal SPI communication error

P06D1 is an internal ignition-coil control performance code. The cited GM strategy detects an SPI information error from the ignition power-stage diagnostic ASIC. This is an internal electronic communication check, not directly a measurement of spark quality at a plug.

Both banks have a documented path

Separate rows cover the bank 1 and bank 2 diagnostic ASIC communication paths under the same code. The five-character code alone therefore does not identify which bank supplied the error without additional fault detail.

The table uses 20 events and one-trip reporting. Engine synchronization is required, speed must exceed 1,400 rpm, and the ignition counter must advance by more than nine counts to establish that all cylinders fired. These conditions distinguish the running check from an unqualified key-on observation.

Preserve the internal error identity

Retain manufacturer-specific substatus and the bank or power-stage context when available. A cylinder misfire counter or a coil resistance measurement cannot directly demonstrate that SPI information was transferred correctly.

The row prints an atypical upper battery-voltage value, which is not adopted as a practical service limit. The source also does not establish whether the underlying cause is in circuitry, data handling or another internal condition. Follow the appropriate module diagnostic procedure before choosing a coil or controller replacement. This code’s value is in identifying a communication-supervision failure within ignition control, rather than automatically condemning an ignition component.

Source and applicability

This explanation covers the cited GM monitor, not every vehicle carrying this code. The application-matrix filename does not resolve cleanly to this file, so no model or engine fitment is assigned. GM diagnostic table, PDF page 636; GM diagnostic table, PDF page 637.