🛠️ Case Study: Mazda BT-50 – DPF Trouble at 308%

🔧 Vehicle Info

- Make & Model: Mazda BT-50- Year: 2017- Engine Code: P5AT2315191- Complaint: Check engine light, no power, suspected DPF fault

🧨 Customer Report

The customer drove to work with no issues. After their shift, the ute wouldn’t start due to a flat battery.A workmate jump-started it — and that’s when the problems began:- Check engine light appeared- The vehicle entered forced limited power mode- It was towed to our workshop

🧪 Initial Observations

- DPF Soot Load (Open Loop): 308%- EGR Pressure Sensor: 0 kPa- Glow Plug Faults: All open circuit codes- EGR Readings: Inconsistent- Battery: 8 years old — original⚠️ The 308% soot load and 0 kPa pressure sensor readings were red herrings.The soot load was a calculated open loop value, not something the ECU was actively reacting to.The EGR sensor showed 0 kPa, but didn’t reflect an actual fault.

308%?

📸 Scan showing 308% soot load:

🔧 Diagnosis and Repair

- Replaced all glow plugs (essential for regen)- Cleaned intake and EGR system- Installed new battery- Reset ECU learned values- Carried out multiple test drives to confirm passive regen occurred

📸 Post-repair PID data:

📸 Sensor readings after cleaning and resets:

✅ Final Outcome

With clean airflow, new glow plugs, and learned values reset, the vehicle returned to normal operation.Passive regeneration resumed and power was restored.

💡 Key Takeaways

- Don’t chase every PID at face value — understand what the ECU actually uses- Ask customers about flat battery or jump-starts- Glow plugs are critical — no regen without them- Clean airflow + ECU resets often bring the system back online

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