Author Topic: O2 sensor code p1040 (Read 892 times)

Jazzsilver2006 · « **on:** April 22, 2023, 05:44:24 PM »

I have a 2006 1.3 dsi. The engine light came on showing code p0140. I’ve changed the o2 sensors and it was still on so I took it to a garage who said the cat must of gone. I changed the cat and still the code is coming up p0140. Any suggestions please?

Jocko · « **Reply #1 on:** April 22, 2023, 07:45:18 PM »

I assume after reading the code you reset it? it could be a bad connection at the plug. It is the O₂ sensor at the back of the cat.

Jazzsilver2006 · « **Reply #2 on:** April 23, 2023, 06:06:30 PM »

Yes it’s the back one and I’ve cleared the code. Maybe, I have sprayed it with contact cleaner.

E27006 · « **Reply #3 on:** May 02, 2023, 04:59:00 PM »

Is there an air-leak in the exhaust at one of the two joints between exhaust manifold and the cat? The cat and sensor working correctly but measuring exhaust gas diluted by free air.
Diagnose Dan fixed such a problem on a Peugeot car, An air leak altered the composition of the exhaust gas,the sensors were fully functional, but the signals going to the ECU did not correlate with expected values, so the ECU was fooled into flaggeing the fully functional sensors as faulty.
Here is the video link to the Peugeot diagnosis.