Diagnostic trouble code (DTC) information

WARNING: This page is about a different car, the 2002 Volvo C70, 2001 Volvo C70, 2000 Volvo C70, 1999 Volvo C70, and 1998 Volvo C70. However, it is still accessible from the selected car via links, so may be relevant.

IMM-235 Key unknown

Condition

NOTE:

Connecting breakout box can store diagnostic trouble code (DTC) IMM-235 because the breakout box cables affect the transponder reading.

Fig 1: Adding/Erasing Ignition Keys

Courtesy of VOLVO CARS OF NORTH AMERICA.

With the ignition on the immobilizer control module reads the transponder. If the transponder replies to the immobilizer control module with an unknown transponder code, which is not approved (not stored in the memory), Diagnostic trouble code (DTC) IMM-235 is stored 2 seconds after ignition is switched on. At least one keycode must be stored in the immobilizer control module for a diagnostic trouble code (DTC) to be stored. Faults which cause diagnostic trouble code (DTC) IMM- 335 can also cause diagnostic trouble code (DTC) IMM-225 to be stored

The diagnostic trouble codes (DTCs) are erased when the counter value is five.

Possible Source

The ignition key is a Volvo key which has the immobilizer control module security code programmed into the transponder memory. The key is not programmed into the immobilizer control module.
The Volvo key is already programmed with a security code which belongs to another immobilizer, generation 3.
Several transponders activated (programmed or unprogrammed) activated in several keys during transponder reading.
EMC interference (strong electrical field) during communication phase (at start)

Fault symptom[s]

The engine can only be started with those customer keys that are correctly programmed.
The engine starts but stalls directly.