My SLK 280 2006 is showing the Check engine light ON and the gear not changing neither by automatic drive or tiptronic drive. checking by computer fault log it shows first the O2 sensor malfunctioning. I change it and the problem appears again after 2 days. Again checking the fault log and it shows the speed sensor malfunctioning. I am not sure ! any idea??

SOURCE: code PO131

Code PO131 is O2 sensor circuit low voltage , bank 1, sensor 1. That sensor I would say is the one in the exhaust manifold. I would check voltage to the sensor from the computer. If the voltage is not 5 volts, then it could be a computer problem or a wiring problem. I have seen factory wiring and connectors give a voltage problem. Check for a damaged or burnt, pinched wire. You need to know for sure that the voltage is correct to the sensor. Intermittent problems are hard to trace , but patience and knowledge helps.

SOURCE: 02 Neon won't shift out of second gear in Drive

Sounds like the valve body is loose, warped or blown

SOURCE: i have a toyota rav4 2003 management light came on

The upper sensors are air fuel sensors and the lower ones are o2 sensors. you cant mix these up. Assuming you did everything right and still coding then either the new sensor b1s2 is bad or the wirng(power and ground need to be checked. A scan tool can be used to look at the performance of the sensors too. Sometimes the codes just point to the area of the problem and changing the part isn't the answer.

SOURCE: 2004 Range rover Check Engine Light

The Range Rover actually has 4 oxygen sensors - 2 in front of the Cat and 2 behind the cat - try to check / replace the other 2

SOURCE: check engine light on, replaced oxygen sensor before catalyst,

• Water or corrosion in the connector
• Loose terminals in the connector
• Wiring burnt on exhaust components
• Open or short in the wiring due to rubbing on engine components
• Holes in exhaust allowing unmetered oxygen into exhaust system
• Unmetered vacuum leak at the engine
• Bad o2 sensor
• Bad PCM