P1462
Heated Catalyst Internal Control Module Checksum ROM Error.
- BMW
- Powertrain
- Manufacturer code
- Medium severity
How this code is built
- P
- SystemPowertrain
- 1
- Defined byThe manufacturer
- 4
- AreaAuxiliary emission controls
- 62
- FaultThe specific fault in that area
What it means
P1462 on a BMW is listed as a Heated Catalyst Internal Control Module Checksum ROM Error. The module responsible for the heated catalyst control failed its own self-test of stored program memory, so the stored checksum did not match the calculated one. This points to a fault inside the control unit or its software rather than a sensor or heater element. Whether the function sits in the engine control unit or a separate module depends on the model and engine, so confirm against the vehicle's own documentation.
Symptoms
- Engine management warning light on
- Fault stored with no obvious change in how the car drives
- Heated catalyst or catalyst warm-up function not operating as normal
- Emissions-related readiness monitors not completing
- Possible failed emissions test
- Other stored faults, or communication faults, from the same control unit
Possible causes
- Internal fault in the engine control unit or heated catalyst control module (memory corruption)likely
- Corrupted or outdated control unit software or calibration, including a failed or interrupted previous updatelikely
- Low or unstable supply voltage to the module, caused by a weak battery or poor chargingpossible
- Poor power or earth connections to the module, or corroded connector pinspossible
- Water ingress or heat damage to the control unit or its connectorpossible
- Previous incorrect or non-approved software modification to the control unitrare
How to diagnose
- Read all stored and pending codes and record the freeze frame data, noting any other module or communication faults
- Check battery condition and charging voltage, and fix any weakness before further testing
- Inspect the control unit and any separate heated catalyst module for water ingress, corrosion, heat damage and loose connectors
- Check power supply and earth connections to the module for voltage drop under load
- Clear the code, then road test and rescan to see whether it returns straight away or only after a restart, which suggests a hard memory fault
- Check the control unit software and calibration level against the latest approved release for that model and engine, and note any failed update history
- Check for service information or technical bulletins covering this code on the specific model, as the affected module varies
How to fix
- Repair any wiring, earth or connector faults found and clear the code
- Correct battery or charging system faults, then recheck the code
- Reprogram the control unit with the latest approved software and calibration if it is outdated or corrupted, keeping the battery supported throughout
- Replace and code the control unit or heated catalyst module if the memory fault persists after reprogramming
- Dry out and repair any water ingress, replacing the module if damage is confirmed
Can I keep driving?
The car can usually be driven short term as this is a fault in the control module's self-check, but get it diagnosed soon. The catalyst may not warm up correctly, which can affect emissions, and the module could fail further.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.
This code for other makes
- P1462FordAir Conditioning Pressure Sensor Circuit High Input
- P1462LincolnAir Conditioning Pressure Sensor Circuit High Input
- P1462MercuryAir Conditioning Pressure Sensor Circuit High Input
- P1462OtherA/C pressure sensor circuit voltage high
- P1462VolkswagenExhaust Gas Temperature Control Bank 2 Range Performance