Across UK garages, the 1.5-litre K9K / OM607 turbodiesel fitted to the Mercedes A-Class (W176), B-Class (W246), CLA (C117), Nissan Qashqai (J11), and Renault Clio/Megane/Kangoo is famous for throwing a sudden 'Check Injection System' warning and dropping into 3,000 RPM limp-home mode. Before you let anyone replace your DPF or turbocharger, inspect the thin rubber-and-metal Exhaust Differential Pressure Sensor Pipe (Mercedes OEM A6071420104 / Renault-Nissan OEM 1412000Q0U) at the back of the cylinder head.
1. Why Carbon Soot & Exhaust Heat Destroy Pipe A6071420104 / 1412000Q0U
This narrow tube transmits raw exhaust gas pressure from upstream of the turbo/DPF up to the 3-pin differential pressure sensor bolted to the upper bracket. Over 50,000 miles of urban UK driving, acidic exhaust condensation mixes with diesel soot to form a rock-hard carbon plug inside the metal bend, while radiant heat from the turbo manifold splits the upper silicone/elastomer connecting sleeve.
2. UK Workshop Diagnostic Fault Codes, Symptoms & Root Causes
| Fault Code / Defect | On-Road / MOT Symptom | Root Cause & Permanent Workshop Fix |
|---|---|---|
| P2452 / P2453 | Particulate Filter Differential Pressure Sensor Circuit / Signal Plausibility | Split rubber sleeve or carbon-choked metal tube on pipe A6071420104 / 1412000Q0U. |
| P1489 / DTC148968 | Exhaust Gas Pressure Upstream of Turbine — Plausibility Error | Exhaust gas leaking from the lower union or blocked pressure feed to the transducer. |
| P2463 / P2002 | DPF Soot Accumulation Too High | ECU unable to verify exhaust backpressure drop during motorway regeneration. |
3. Verified OEM Part Number Cross-Reference & UK Fitment Guide
| OEM Reference | UK Vehicle Application | Component & Workshop Spec |
|---|---|---|
| BD1168 — A6071420104 / 1412000Q0U | Mercedes A-Class W176, B-Class W246, CLA C117, Citan (1.5 CDI OM607) | Complete Exhaust Differential Pressure Sensor Pipe & High-Temp Hose |
| BD1168 — 208744694R / 1412000Q0T | Nissan Qashqai J11, Juke, Note & Renault Clio IV, Megane, Captur, Kangoo 1.5 dCi | Direct OEM-Spec Exhaust Backpressure Sensor Pipe Assembly |
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4. Step-by-Step UK Workshop Fitting Procedure & Torque Specs
- Soak the Lower Exhaust Boss While Warm: Spray penetrating oil onto the lower threaded union on the exhaust manifold/DPF housing 15 minutes before loosening.
- Release the Upper Sensor Hose Clamp: Unclip the spring clamp where the heat-resistant rubber hose joins the 3-pin exhaust pressure sensor spigot—pull straight upwards so you do not snap the plastic sensor nipple.
- Install the New BuyDay BD1168 Pipe Assembly: Thread the lower union in by hand first, tighten to 18 Nm, and secure the upper spring clamp onto the pressure sensor port.
- Clear Learned Pressure Sensor Offset: Use your diagnostic tablet to clear P2452/P2453 and reset the differential pressure sensor zero-offset adaptation with ignition ON, engine OFF.
5. Master Mechanic Q&A: UK Workshop & MOT Questions Answered
Q: Does Mercedes A180d part A6071420104 fit the Nissan Qashqai and Renault Clio 1.5 dCi?
Dave Mercer (Master Tech): Yes. The Mercedes 1.5 CDI (OM607) is based on the Renault-Nissan 1.5 dCi (K9K) engine, so Mercedes A6071420104 and Nissan/Renault 1412000Q0U / 208744694R are identical components.
Q: Can a split exhaust pressure sensor pipe cause a pungent exhaust smell inside the car?
Dave Mercer (Master Tech): Yes. Raw pre-DPF exhaust gas hissing out of a split A6071420104 hose rises directly beneath the windscreen scuttle panel and gets drawn into the cabin heater blower.
📚 Related UK Workshop Diagnostic & Replacement Guides
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