P26C9: Chassis Control Module 2 Requested MIL Illumination

What it means

A second chassis control module has signalled an emissions-relevant fault and requested the engine controller to switch on the MIL.

At a glance

• Usually lights the check-engine light

How it works

A second chassis control module, such as one managing active suspension, AWD, or steering, can request the engine controller to illuminate the malfunction indicator lamp when it flags a fault as emissions-relevant. P26C9 records the request from chassis control module 2, so the underlying problem must be identified from that module’s own codes.

Common causes

Most likely first.

1. Active DTC stored in the chassis module
2. Communication loss interpreted as MIL request

Symptoms

• Check-engine light may be on
• Chassis or drivetrain warning light may also be on
• Stability, steering, or AWD functions may be limited

How to diagnose it

1. Scan all modules, especially chassis control module 2, and record its active and history codes before clearing anything.
2. Review event or freeze-frame data in module 2 to identify which chassis function was affected when it requested the MIL.
3. Check the vehicle display for related steering, stability, suspension, or AWD warnings and note any limited function.
4. Inspect module 2 power, ground, connectors, and network wiring if its codes point to a communication or supply problem.
5. Repair the specific fault stored by module 2, then confirm that its MIL request clears after a system check.

Common fixes

• Repair the underlying fault identified in chassis control module 2.
• Restore a loose or corroded module 2 power, ground, or connector connection.
• Repair damaged communication wiring if module 2 reports lost communication.
• Replace or reprogram module 2 only if its own fault is confirmed by the manufacturer's diagnostic procedure.

Can I keep driving?

If steering, stability, suspension, or AWD functions are limited, drive cautiously and avoid conditions that rely on those systems; stop if steering or stability feels unsafe. Read module 2 codes promptly because this request code does not identify the underlying fault.