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marcowilliams1

C4 Manifold Pressure Sensor Issue

I have a 2005 Citroen C4 diesel with 167445 km. The check engine light is on, engine power is down, response is poor, and fuel consumption is up. I think the manifold pressure sensor might be bad and suspect a vacuum leak. Anyone else had this on their C4?

4 comment(s)

marcfox20

I had similar symptoms on my C4. The ECU uses the manifold pressure sensor to measure air pressure, which is critical for calculating the air-fuel mixture. If the sensor fails, the ECU can't regulate fuel injection, causing reduced power and increased fuel consumption. Did you check the sensor's wiring and vacuum lines? A loose connection or cracked hose could be the problem.

marcowilliams1 (Author)

Thanks. I visually checked the wiring and vacuum lines, but didn't test them thoroughly. Can you explain the specific checks I should do on the sensor and vacuum lines to confirm the fault?

marcfox20

Given your symptoms and what you've found, it sounds like a faulty manifold pressure sensor or a vacuum leak. You could test with a multimeter or smoke test the vacuum lines, but a workshop assessment might be best, considering the complexity and the sensor's cost.

marcowilliams1 (Author)

I took the C4 to my mechanic. The manifold pressure sensor was faulty, like we thought. Repair, including sensor replacement, cost 235€. Thanks for the help; it made me confident to get it sorted quickly.

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