Hello All,

I own a volvo s40 2.4i 2005 with 211,000 km. The code P00131 sensor 1 bank 1 was there for about 1 month or so. I decide to change the front Oxygen sensor this saturday.

Since then, the car is not running good at all, but the check engine is not there anymore. I have drive more then 100 km.

When am over 2500 RPM, the car is hesiting and its like going forward and backward.... very weird sensation. When Idle the rpm also moving a little bit.

Anybody have idea ? I have change de Fuel pressor sensor around when the car was 160,000k.

 

Now the check engine P0131 is back on... Bad oxygen sensor maybe ??

 

I have reset the ECU ... no luck.

Anybody know ?

 

when you say "reset the ECU" do you mean you used an OBD2 scanner to clear the codes or you tried to pull out the ECU and replaced it to see if that cleared the code? Sounds like you may have a bad connection to the O2 sensor or the unit you installed was not correct for your model S40. Start by checking the connector, then check voltages if you can (ie probe into the back side of the connector). Google "testing O2 sensors" to get some ideas on what to expect - you may even find a helpful Youtube vid.

 

Can you replace the new sensor with the old one? If you go back to the old sensor and the problems go away you have isolated the problem to the new sensor.

If you cannot go back to the old sensor try disconnecting the new sensor. Normally this causes the ECU to use a set table for fuel trim. It will normally run a bit rich but run better. It will tell you if the new sensor is giving the ECU bad input.