P0470: Exhaust Pressure Sensor A Circuit
What to do
Often driveable at first, but do not leave it. On a diesel this sensor governs particulate filter regeneration, and a filter that never regenerates will eventually block and require specialist cleaning or replacement. Mention any recent history of short journeys, which make the problem worse.
What this code means
A fault in the exhaust back-pressure sensor. On a diesel this is one of the more consequential sensors on the engine, because it is how the module knows how full the particulate filter is: soot accumulating in the filter raises back pressure, and the pressure differential across it is what triggers regeneration.
A sensor the module cannot trust means regeneration cannot be scheduled sensibly — either it never runs and the filter blocks, or it runs constantly and dilutes the engine oil with unburnt fuel. Neither is visible until it becomes expensive, which is why this code deserves more attention than its usually unremarkable symptoms suggest.
Likely causes
Start here
- Faulty exhaust back pressure sensor · moderate
- Blocked or kinked sensor line · moderate
- Damaged wiring harness near exhaust heat · moderate
- Corroded or loose connector · easy
Symptoms
Components involved
Information, not instruction
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Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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