1) What is the EGR system and why it exists

Сайт EGR (Exhaust Gas Recirculation) system recirculates part of the exhaust gas back into the intake to
reduce combustion temperature and lower NOx emissions.
In petrol engines it dilutes the mixture with inert gases; in diesel engines it decreases oxygen concentration.
This reduces NOx formation but slightly increases soot and reduces volumetric efficiency.

2) Typical faults and symptoms

• Carbon build-up and oil vapour deposits clogging valve or cooler;
• Vacuum or actuator faults preventing full closure/opening;
• Leaking EGR valve causing unmetered air and unstable idle;
• Pressure differential or temperature sensor faults;
• Frequent MIL / DTC: “EGR flow insufficient/excessive”, “EGR stuck open”.

3) Diagnostic checklist

• Read all DTCs and log live data before modifying;
• Compare commanded vs actual EGR position, MAF, MAP, and EGT;
• Inspect vacuum lines, solenoids, EGR cooler, and manifold joints;
• Physically test valve movement and sealing integrity;
• Check for oil or soot leakage around the valve seat;
• Ensure ECU software is updated before calibration.

4) Software vs. Hardware EGR Off

A) EGR Off by software (ECU remap)

The standard approach for modern ECUs: deactivate the EGR logic, maps and DTCs.
A correct air model recalibration keeps MAF/MAP coherence and prevents limp mode.
When correctly done, diagnostics remain satisfied, with no warning lights or fallback strategies.

B) Mechanical blanking (hardware)

If the EGR valve is old, clogged, leaking or unable to close fully, a software delete alone is not enough:
residual gas flow will still affect intake readings and combustion stability.
In such cases, a blanking plate (solid gasket with no hole) must be installed to ensure complete mechanical closure,
followed by the correct software EGR off.
Plate + software together provide long-term reliability and a clean intake manifold.

5) Software EGR Off procedure

1. Read and back up the original file (OBD / Bench / Boot).
2. Identify EGR maps and switches (flow request, limits, plausibility, temperature).
3. Set EGR duty/request to 0 % in all relevant zones.
4. Deactivate only EGR DTCs (flow, position, plausibility).
5. Correct checksum and reflash the modded file.
6. Reset EGR-related adaptations and clear old DTCs.
7. Test drive under various loads; confirm no errors or smoke.

6) Post-tuning checks

• Check live data for correct MAF/MAP and zero EGR flow;
• EGT and coolant temperature stable under load;
• No DTCs or smoke during acceleration;
• Idle smoothness and throttle response improved;
• Fuel consumption consistent with stock values.

7) Quick FAQ

Does EGR off damage the engine?

Not if properly tuned. Air-model and thermal management must remain coherent. Poorly edited files may increase NOx or EGTs.

Do I need to blank the valve?

Yes, if the valve leaks, sticks, or no longer seals. A blanking plate ensures mechanical isolation and correct air readings when software EGR off is applied.

Can I disconnect the EGR plug?

Always follow the specific instructions published on the official TuningBot EGR section:
steps differ by ECU type and configuration.
See tuningbot.com/tuning/egr/ for official guidance.