Review on 🔧 Grey Denso 234-9009 Oxygen Sensor by Mark Sharma

My wife's Highlander started showing up with CEL codes P0135 and P0155. The original parts measured just over 2.5 ohms in the heating element (two black wires), while the Highlander needs a reading of around 1.5 ohms. Luckily this was documented on the forums so I could verify that these parts really needed to be replaced. That's what you need to replace. On a 2003 Highlander you can fit the torque arm to the sensor closest to the firewall by running along the driveshaft to the rear of the car (look at the catalytic converter sensor and its heat shield - there is a gap underneath). Catalyst housing to put a torque wrench along the driveshaft to get to that sensor and turn the wrench) - vs is the barely accessible gap just below the sensor. With them I swapped out both sensors in less than 2 hours even when I thought I was running very slowly.