P0470: Exhaust Pressure Sensor "A" Circuit

P0470 is a emissions-related diagnostic trouble code classified as moderate severity.

• Check engine light on
• Often no change in how the car drives at first
• DPF warning light on some models, sometimes appearing later because regeneration has stopped
• Reduced power or limp mode on some vehicles
• Higher fuel consumption if the engine falls back on an estimated value
• P0471 stored alongside on some cars

Generally yes, for short-term driving. Driveable in the short term, and the car often feels normal at first. Do not leave it for weeks: without a trustworthy exhaust pressure signal the engine computer may suspend particulate filter regeneration or fall back on an estimate, and some cars limit power. A filter that goes too long without regenerating can block, which turns a sensor, hose or wiring repair into a DPF clean or replacement.

1. Read all stored codes and the freeze frame. Note whether P0471 or a DPF code (P2452 to P2455, P244A, P244B or P2463) is stored alongside, because a loaded filter changes the plan. A generic OBD2 reader shows this code, its freeze frame and standard live data. A few diesels also report exhaust or DPF pressure on a standard PID, but on most cars the pressure reading, the soot load and the regeneration history need manufacturer-level software, and only that software or a workshop can run a forced regeneration or adapt a new sensor.
2. Find out which sensor is exhaust pressure sensor "A" on your engine: a back pressure sensor near the exhaust manifold or turbo, a sensor before the particulate filter, or on many Volkswagen group TDIs the DPF differential pressure sensor. Check the workshop information for your engine code before buying a part.
3. Check the fuse for the sensor supply, then unplug the sensor and inspect the connector for corrosion, water and pushed-back pins.
4. With the key on and the engine off, measure the 5 V reference and the ground at the connector. A missing reference or ground points to the wiring or the engine computer, not the sensor.
5. Back-probe the signal wire. The signal should sit at a steady value with the engine off and rise smoothly with revs once it is running. A signal stuck near 0 V or near 5 V, or one that drops in and out, points to the circuit or the sensor.
6. Follow the harness from the sensor, especially where it passes the turbo, exhaust pipes or DPF, and look for melted insulation or chafing. Wiggle-test it while watching the signal.
7. If the circuit tests good, replace the sensor with the correct part for the engine code, run the sensor adaptation if the engine computer asks for one, clear the code and road-test. If soot built up while the sensor was out, a forced regeneration may be needed afterwards.