OBD-II Code P2958 — What It Means & How to Fix It

What it means

P2958 means the message counter from the security sensor module is out of sequence or incorrect on the vehicle's CAN bus network.
This indicates communication errors between the security module and other modules on the network.
In some cases, it may trigger anti-theft modes or prevent the engine from starting.

Affected Models

All vehicles 1996+ with CAN bus networks
Common in GM vehicles with factory security systems
Common in vehicles with aftermarket security systems added
Common in vehicles with aging or failing 12V batteries

Common Causes

Faulty security module generating incorrect message data
CAN bus communication fault causing dropped or corrupted messages
Low battery voltage causing module resets and counter mismatches
Damaged CAN bus wiring causing data corruption
Aftermarket security system interfering with factory security module messages

How to Fix It

Check the vehicle battery — low voltage causes many module communication faults.

A weak battery (below 12.4V resting) causes modules to reset repeatedly, disrupting message counters across the entire CAN bus network.
Scan all modules with a full-system scan tool and check for CAN bus error codes.

A full-system scan reveals whether this is isolated to the security module or part of a broader CAN bus communication failure.
Inspect CAN bus wiring for damage, shorts, or open circuits.

The CAN bus uses two wires (CAN High and CAN Low) — damage to either causes widespread module communication faults across the vehicle.
Remove any aftermarket security devices and retest.

Aftermarket systems that tap directly into factory wiring can corrupt CAN bus messages — removing them often resolves the fault immediately.
Have the security module reprogrammed or replaced if the fault persists.

A security module that generates incorrect message counters cannot be reset by clearing codes — reprogramming or replacement is required.

When to Call a Professional

A CAN bus communication fault requires a full-system scan tool — a standard code reader is not sufficient.
A technician will scan all modules for CAN faults, check battery voltage, and inspect CAN bus wiring.
Security module reprogramming costs $100–$300; module replacement runs $200–$600+.

Frequently Asked Questions

Could an aftermarket alarm cause P2958?

Yes.
Aftermarket systems that tap into factory wiring can disrupt CAN bus communication messages.
Removing or properly integrating the aftermarket unit often resolves this code entirely.
If an alarm was recently installed, that is the first thing to check.

Can a dead battery cause P2958?

Yes.
When the battery drops below normal operating voltage, modules reset and lose message counter synchronization.
Replace a failing battery and clear the codes first before pursuing more complex diagnosis.
Many P2958 cases resolve after a fresh battery is installed.

Is P2958 a theft risk?

Not directly — it is a fault in the communication system, not the security function itself.
But a failing security module could potentially affect anti-theft operation over time.
Have it evaluated by a dealer or security specialist to confirm the system is still functioning properly.