Mercedes C-Class Blocked DPF Fix (P2463) With a Dead Exhaust Temp Sensor

for business enquiries email [email protected] www.orileysautos.com The engine management light was on when this Mercedes C-Class showed up, and I already knew it had some sort of DPF issue. Mileage was showing 134,000 miles, which is the sort of number where soot load problems start to show up if the car’s been doing lots of short runs. A quick scan would tell me whether this was just a blocked filter, or something stopping the car from sorting itself out. Plugging in the diagnostic tool (Launch X431 Euro) from www.launchtech.co.uk I plugged in and went straight into Intelligent Diagnose. I always choose the enhanced scan, because it checks every module on the car. It takes longer, but it stops me missing a second fault that’s causing the main one. Full scan results: the fault codes that mattered The scan finished with two faults in the CDI unit (engine). Some other items popped up too, but they weren’t part of this job. Here are the key engine-related codes: P2463 Blocked DPF P242DTemperature sensor 3 exhaust system bank 1, short circuit P246309 Redundancy system activated Live data check: why the DPF couldn’t regenerate Next I checked live data to see what the DPF system was actually doing. On this setup, the exhaust temperature sensors sit like this: Sensor 1: upstream of the turbo Sensor 2: downstream of the catalytic converter Sensor 3: downstream of the particulate filter (DPF area) Sensor 3 was stuck at 300°C. I revved the engine and sensors 1 and 2 responded, but sensor 3 didn’t move at all. That backed up the fault code, it looked like a dead sensor, and a dead temp sensor can stop a car from doing a proper regeneration. DPF values also looked bad: Differential pressure: about 25 mbar Fill level: 400% Stripping down to access the sensor and DPF area To get access, I started stripping the top down. My rough order was: 1. Remove the engine cover. 2. Disconnect the pipes carefully (they’re delicate). 3. Undo the airbox clamp (7 mm or a screwdriver). 4. Remove the ECU screws and move the ECU aside. 5. Lift out the airbox. I could see a temperature sensor from the top, but not sensor 3, which confirmed it was underneath. Replacing exhaust temperature sensor 3 (and the wrong part problem) I ordered a sensor from Mercedes, explained what I needed, and they sent the wrong one. It was for the first position, before the turbo, not the one I needed after the DPF area. So I got the car up and fitted the correct sensor underneath. Once fitted, the live reading stopped sitting at 300°C and started rising and falling with revs, exactly what I wanted to see. Cleaning the DPF with Launch UK DPF training fluid With the sensor sorted, I moved on to the DPF cleaning. I unbolted the bracket (three bolts), disconnected the pressure sensor pipe, and confirmed I was on the correct side using a digital manometer. With the engine running, I sprayed Launch UK DPF fluid into the DPF at 120 PSI until it pushed through. Then I held the revs for 2 to 3 minutes. Expect smoke here, that’s part of the process. I watched pressure drop down to about 6 to 7 mbar at idle, then later I saw it down at 2 mbar. Teach-in process: resetting DPF learned values and clearing codes After cleaning, I had to run the teach-in process (special functions). There’s no real workaround on this car, I needed to tell the ECU it had a “new” DPF. That reset the DPF fill level to 0%, which then allowed me to clear the fault codes properly. I read DTCs first, then cleared them, and started the engine to confirm the warning light stayed off. Final checks: pressure, fill level, and temperature readings At the end, the numbers looked right: DPF pressure: 2 mbar Fill level: 0% Temperature sensor readings: moving properly with revs Conclusion This Mercedes C-Class came in with a blocked DPF code, but the real stopper was a failed exhaust temperature sensor that would prevent regeneration. Once the correct sensor was fitted and the DPF was cleaned, the teach-in reset brought the system back to normal. If there’s one takeaway, it’s this: fix the input faults first, because the DPF can’t manage itself without good data. If you’ve had a similar DPF warning, check the live readings before you throw parts at it.