Here’s a concise, practical description for the Proton Saga FLX (2014) — CVT — ECU with code ''0042'' / part number PW910042.

What it is

• Part number / code: PW910042 (code shown as 0042 on many listings).  
• Supplier / OEM: Market listings identify this as a genuine Proton unit built on a Continental ECU platform (Continental-sourced engine control module).  

Main functions

• Manages engine operation: fuel injection, ignition timing, air–fuel control, idle control and emissions strategies.
• Interfaces with the CVT/TCU and drivetrain via CAN/serial communications for coordinated control (engine ↔ transmission).
• Handles on-board diagnostics (stores fault codes / MIL check), and usually integrates immobiliser/anti-theft authentication or works with an immobiliser module.
  (Those are standard ECU responsibilities for this vehicle class; the PW910042 implements these for the Saga FLX CVT).  

Compatibility / fitment

• Specified for Proton Saga BLM / FL / FLX equipped with the 1.3 CVT (CVT2) configuration — confirm engine and gearbox match before replacement. Listings explicitly state suitability for Saga FLX CVT2.  

Installation / programming notes

• Many sellers note ''Plug & Play: NO'' (i.e., replacement may require coding/programming to pair immobiliser keys, VIN and vehicle-specific calibrations). Expect workshop ECU programming or module swapping by a qualified workshop if unit is not pre-matched. Always verify with seller whether the unit is pre-programmed.  

Condition & price guidance

• Common market options: new (genuine), remanufactured, or used units. Prices observed in Malaysian listings vary (roughly a few hundred ringgit for used units; new/genuine list higher). Example product listings show used units ~RM400–RM700 depending on seller/condition.  

Symptoms of a failing ECU (what to check)

• Engine not starting or intermittent cranking without fire.
• Check Engine Light / MIL on with multiple or odd fault codes.
• Poor idle, sudden stalling, hesitation, or loss of power.
• Communication errors on diagnostic tool (no response from ECU) or CAN bus faults.

Practical tips before buying/replacing

1. Confirm part number & code (PW910042 / 0042) on your existing unit before buying.  
2. Ask seller whether the unit is pre-coded to your car’s VIN/immobiliser; if not, arrange for ECU programming (dealer or a workshop with the right Proton/Continental tooling).  
3. Prefer OEM or known-good reman units; request a short warranty where possible.  
4. If swapping a used unit, bring your keys and diagnostic tool so the installer can confirm immobiliser/key pairing and clear/retest fault codes.

If you want, I can:

• show several current listings (price + photos) for PW910042 (0042) so you can compare; or
• help draft the exact questions to ask a seller or workshop (e.g., ''Is this ECU coded to VIN X? Will it require immobiliser programming?'').

Which would you like next?