P0602
Control Module Programming Error.
- Generic
- Powertrain
- Generic code
- High severity
How this code is built
- P
- SystemPowertrain
- 0
- Defined bySAE, the same on every car
- 6
- AreaComputer and output circuits
- 02
- FaultThe specific fault in that area
What it means
P0602 is the generic code for a control module programming error. The module's self-checks found that its software, calibration data or coding is missing, corrupt, incomplete or does not match the hardware. It can also be set after a failed or interrupted update, or when a replacement unit has not been programmed or coded correctly.
Symptoms
- Engine management warning light on
- Engine cranks but fails to start, or starts and stalls
- Reduced power or limp-home mode
- Poor running, hesitation or erratic idle
- Gearbox stuck in one gear or harsh shifts, where the module also controls the transmission
- Other warning lights or communication faults appearing at the same time
Possible causes
- Failed, interrupted or incomplete software or calibration updatelikely
- Replacement or second-hand control module not programmed, coded or matched to the vehiclelikely
- Low battery voltage or unstable power supply during programming or operation corrupting the datapossible
- Corrupted memory or internal fault in the control modulepossible
- Wrong or outdated software or calibration version for the engine or modelpossible
- Poor module power or earth connections, or damaged wiring and connectorspossible
- Water ingress or physical damage to the control modulerare
How to diagnose
- Read all stored and pending codes and note the freeze frame data, including whether other modules have set communication or programming faults
- Ask about recent work: module replacement, software updates, coding changes, battery disconnection or jump starts
- Check battery condition and charging voltage, as low or unstable voltage can corrupt data and interrupt programming
- Inspect the module's power and earth connections, fuses, connectors and wiring for corrosion, damage or moisture
- Check the module for water ingress, heat damage or physical damage
- Clear the code and retest to see if it returns straight away or only under certain conditions
- Check the module's software and calibration version against the latest available for the exact vehicle, engine and model year
- Confirm that a replacement module is the correct part number and has been programmed and matched to the vehicle, including any immobiliser matching
How to fix
- Reprogram the module with the correct, up-to-date software or calibration for the vehicle, using a stable power supply
- Correctly program, code and match a replacement module to the vehicle, including immobiliser and security adaptation where required
- Repair or replace faulty power, earth or wiring connections to the module
- Replace or recharge a weak battery, then repeat the programming
- Replace the control module if the memory or internal hardware is faulty and reprogramming does not cure it
Can I keep driving?
High severity
Avoid driving until the fault is diagnosed, as the engine or gearbox may not run correctly and could cut out or go into limp mode without warning. If it is running normally, only drive it a short distance to a workshop.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.