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P1260

Last Test Failed SCC Or Theft Detected Vehicle Immobilized.

  • Cadillac
  • Powertrain
  • Manufacturer code
  • High severity

How this code is built

P
SystemPowertrain
1
Defined byThe manufacturer
2
AreaFuel and air metering (injector circuit)
60
FaultThe specific fault in that area

What it means

On a Cadillac, P1260 means the engine control module logged that the last security check failed or a theft condition was detected, so the vehicle has been immobilised. The ECM expects a valid security or password message from the anti-theft system (SCC here refers to the security code check) and did not receive a correct one, so it limits or stops fuel and/or starting. The exact security architecture depends on the model and year.

Symptoms

  • Engine cranks but will not start
  • Engine starts then stalls after a second or two
  • Security or theft warning light on or flashing in the instrument cluster
  • No start after the key, battery or ECM has been replaced or disconnected
  • Intermittent no-start that comes and goes with different keys or key positions

Possible causes

  • Key not recognised: worn, damaged or unprogrammed transponder, or a key that has lost its codinglikely
  • Security data mismatch after replacing or reprogramming the ECM, body control module or other security-related modulelikely
  • Poor or faulty communication between the security module and ECM, such as wiring, connector or data line faultspossible
  • Weak or recently disconnected battery causing a corrupted security handshake or low voltage during the checkpossible
  • Faulty ignition lock cylinder, key reader or immobiliser antenna/coilpossible
  • Genuine attempted theft or tampering, or an aftermarket alarm or remote-start device interfering with the security signalrare

How to diagnose

  1. Read all stored and pending codes plus freeze frame data, and note any other security, body control or communication codes
  2. Try every available key, one at a time, and check whether the security light behaviour changes
  3. Inspect the key for damage and check the ignition lock area, key reader and surrounding wiring and connectors for damage or water ingress
  4. Check for any aftermarket alarm, tracker or remote-start fitted and see whether it interferes with the ignition or security wiring
  5. Test battery condition and charging voltage, and check battery and earth connections for security and tightness
  6. Check the security data line and the module power and earth supplies against the wiring diagram for your model
  7. Use a scan tool that supports the security system to view security status and confirm whether the ECM and security module data match
  8. Follow the manufacturer's procedure for the specific model to check whether the ECM and security module need relearning or reprogramming

How to fix

  • Reprogram or replace the key and carry out the security relearn procedure for your model
  • Replace or repair the damaged key reader, ignition lock cylinder or antenna as found
  • Repair wiring, connector or earth faults on the security data and supply circuits
  • Restore battery health or replace a weak battery, then repeat the security relearn
  • Carry out the manufacturer's ECM and security module synchronisation or reprogramming procedure after any module replacement
  • Remove or correct any faulty aftermarket security device wiring

Can I keep driving?

High severity

The car may not start or may stall, so it may not be drivable at all. If it does run, do not rely on it, as it could cut out without warning and leave you stranded; have it checked before further use.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.

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