Hot Start Fix — Engine Warm Restart Calibration

Hot start fix is a professional ECU calibration service that resolves common warm engine starting issues found in many diesel and petrol vehicles.
Over time, some cars develop a condition where the engine requires several crank revolutions before starting when it is hot, even though it starts normally when cold.
This happens due to the ECU’s start fuel and timing maps being optimized for emissions and not for ageing engines or components.
Our hot start fix adjusts these parameters, improving warm start performance, protecting the starter motor, and ensuring instant ignition under all temperature conditions.

Why hot start problems occur

In many modern ECUs, the quantity of injected fuel and injection timing during engine cranking are temperature-dependent.
When the engine is hot, the ECU often reduces fueling to minimize emissions, but as components wear (injectors, compression, fuel pressure regulator, sensors), the reduced injection is insufficient for immediate combustion.
This leads to extended cranking times, additional stress on the starter motor, battery, and flywheel, and eventual component fatigue.
The hot start fix rebalances these values, providing optimal fueling and timing for faster starts without compromising emissions or engine safety.

How the hot start fix works

Our engineers modify the ECU maps that control cranking fuel delivery and start-of-injection timing relative to coolant temperature.
This correction ensures that even when the engine is warm (typically 60–90°C coolant temperature), the ECU injects the right amount of fuel for instant ignition.
The hot start fix does not interfere with idle control, cold-start enrichment, or post-start emissions strategies.
Every file is bench-validated and dyno-tested to confirm smooth start behavior across all operating temperatures.

When the hot start fix is recommended

• When the engine cranks longer or fails to start quickly when warm.
• After replacing or repairing the starter, injectors, or fuel system but the issue persists.
• For older diesel engines (EDC15/EDC16/EDC17) prone to hot start calibration issues.
• To prevent excessive wear on the starter motor, flywheel, and battery caused by repeated warm cranking.

Benefits and technical notes

– Instant warm restarts, reducing crank time and stress on mechanical parts.
– No impact on cold-start behavior or fuel consumption.
– Extends starter and battery life by minimizing unnecessary load.
– Works on both diesel and petrol ECUs (Bosch, Siemens, Delphi, Denso families).
– Fully software-based; no wiring modifications or hardware changes needed.

Important: Hot start fix is not a temporary workaround—it permanently recalibrates the ECU maps responsible for start fueling and timing.
Always ensure that injectors, glow plugs (for diesel), and sensors are in good working condition before applying the modification.

Supported ECU families (examples)

• Bosch EDC15, EDC16, EDC17
• Siemens SID801/803/804
• Delphi DCM families (DCM3.x / DCM6.x)
• Denso and Magneti Marelli systems (selected models)

The coverage expands continuously. If your ECU is not listed, contact our support team for compatibility confirmation.