Ford Mondeo P269F:00-28 & P246B:00-2F & P246C:00-AF & P2463:00-AF

Diagnosing and Fixing Ford Mondeo DPF and Vaporizer Issues

A Ford Mondeo with 147,000 miles on the clock presented a recurring problem with the engine management light. The main trouble centred around the diesel particulate filter (DPF). Despite multiple visits to a garage, the warning light kept coming back. The vehicle had undergone forced regens, a vaporizer replacement, and even a new DPF was fitted, but the fault persisted. The DPF light flashing on and off every few days showed that the problem needed a fresh, careful diagnosis.

Understanding Common DPF Fault Codes

The diagnostic scan revealed several block DPF fault codes. One key code flagged was “Block TPF conditions incorrect,” indicating the car wasn’t able to complete a regeneration cycle. The root of these codes pointed to a problem with the exhaust after-treatment glow plug circuit—also known as the vaporizer circuit. If this circuit is faulty, the system will refuse to start the regen because the vaporizer can't preheat the DPF properly.

The Role of the Vaporizer and Its Fuse in DPF Regeneration

During diesel filter regeneration, the vaporizer heats up to burn off soot. If its fuse blows, the vaporizer won’t activate, and the regen will fail. Problems arise when only parts are replaced in the wrong order. The proper repair steps are:

1. Replace the vaporizer
2. Change its fuse
3. Clean the DPF
4. Reset the system

Skipping the fuse change, for example, means the new vaporizer won’t work properly. That leads to repeated fault codes and ongoing issues.

Diagnostic Tools and Testing Approach

A Launch X431 Euro diagnostic tool was used to scan the vehicle, displaying the fault codes and live data. To test the vaporizer circuit, a multimeter checked continuity and voltage across the fuse. This approach helps confirm if the fuse is intact and whether the vaporizer is receiving power, essential for successful regeneration.

Customer’s Repairs and Common Mistakes

The customer had replaced the vaporizer and fuse themselves but hadn’t reset the fault codes afterwards. Without resetting the system, the car will keep showing the errors even if the parts are fine. This step is critical — ignoring it leads to repeat visits and frustration.

Testing the Fuse and Vaporizer Circuit

Testing revealed the fuse was not blown after the customer’s replacement. Continuity and voltage checks confirmed power was reaching the vaporizer circuit. These tests ruled out a fuse problem, confirming the vaporizer was likely functional.

Assessing the DPF Condition with Pressure and Soot Levels

Pressure readings showed about 30 millibars, a sign of heavy blockage for a relatively new DPF. Soot levels were high too, making it unsafe to start a regen. Before cleaning, it was important to confirm the pressure sensor pipe wasn’t blocked. If blocked, fluid wouldn’t flow inside the DPF and cleaning wouldn’t work.

DPF Cleaning Process Using Launch UK Fluid

Using Launch UK DPF cleaning fluid, the new DPF was cleaned under 120 PSI pressure. The cleaning fluid forms a foam that helps remove soot layers inside the filter. During the process, checking the metal pipe connected to the pressure sensor ensured it was not clogged or damaged, which could otherwise cause false blockage readings.

Attempting DPF Regeneration and Resetting Values

Attempts to manually trigger a static regen through the scan tool failed; the car didn’t respond. The DPF saturation values and fault codes were reset, but the vaporizer cannot be directly turned on without a regen command. Limitations in diagnostic devices mean the vehicle’s ECU controls when regeneration happens.

Road Testing and Monitoring Regeneration Parameters

A test drive to induce passive regen showed the DPF temperature rising but only reaching around 550 to 560°C. This is below the ideal 600°C+ needed for proper regeneration. Interestingly, temperature dropped when driving harder, likely due to poor quality of the aftermarket DPF. Stationary temps were higher, confirming inconsistent heat.

Final Diagnosis: Vaporizer vs. DPF Quality

The vaporizer and fuse were confirmed as fine after all tests, as the fuse hadn’t blown again. The main suspect is the low-quality aftermarket DPF that won’t reach or hold the temperatures needed for cleaning. The recommendation is to reinstall the original DPF to compare performance and condition. If the problem continues, future fault codes for low DPF temperature may appear.

Skipping any step often causes the problem to come back, wasting time and money.

What to Expect Next: Monitoring and Follow-up

Reinstalling the original DPF and monitoring the vehicle over the next few hundred miles will show if the issue is truly resolved. If needed, a follow-up assessment will provide more insights. This case highlights the value of methodical diagnostics and repair sequencing to tackle persistent DPF problems.