Suzuki Swift Melco MH8104 need you help for dtc off

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Sahil670 said:
Vehicle 1: Suzuki Swift 2008
ECU: Melco MH8104
Request: P0420, P0171, P0172 OFF
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Hey there,

For your Suzuki Swift 2008 with the Melco MH8104 ECU, here's some guidance on removing those DTCs:

Requested DTCs:
  • P0420 – Catalyst System Efficiency Below Threshold (Bank 1)
  • P0171 – System Too Lean (Bank 1)
  • P0172 – System Too Rich (Bank 1)

Important Notes

P0420: This is a straightforward catalyst efficiency DTC. You'll need to locate the rear O2 sensor monitoring maps/diagnostic masks in the calibration and disable the catalyst monitoring routine. On Melco ECUs, this is typically done by modifying the DTC enable/disable mask table.

P0171 & P0172: These are fuel trim related codes. Before just disabling them in software, I'd strongly recommend checking for actual mechanical/vacuum issues first:
  • Intake manifold leaks or сrаскed vacuum hoses (common cause of P0171)
  • Faulty MAF sensor or dirty air filter
  • Injector issues or fuel pressure problems
  • Exhaust leaks before the front O2 sensor

Disabling P0171/P0172 without fixing the root cause can lead to poor running conditions, increased fuel consumption, and potential engine damage. These codes exist to protect the engine from running too lean or too rich.

If you still want all three removed via software: You'll need to work with the DTC configuration table in the MH8104 calibration area. Each DTC has an enable/disable bit in the diagnostic mask. Setting the corresponding bits to "disabled" will prevent the ECU from flagging those codes.

Could you share the original read file (BIN/ROM)? That way someone with experience on Melco units can pinpoint the exact offsets for the DTC masks and provide a modified file.

Also, please confirm:
  • Is this a 1.3L or 1.5L engine?
  • Has the catalytic converter been removed or is it still in place?
  • Are the P0171/P0172 codes currently active or stored/pending?

This info will help provide a more accurate solution.
 
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