How to replace pre-cat (O2) sensor on the BMW E46 M3 DIY
How to replace pre-cat BMW E46 M3 (O2) sensor DIY Check engine came on found faulty O2 Lambda sensor on my E46 M3 so thought I'd post a few pics to help others. I bought Bosch sensors from eBay for around $58 each after the fuse blew on a track day and the car went into limp mode. The diagnostics said Sensor 1, Bank 1 heater failure, which I interpreted as the internal heater element in the sensor was shorting and blowing the fuse. Tools You will need: - Metric socket set with plenty of extensions (10", 12") and universal joint adapter to get into angles - 10mm and 13mm spanners - hex bolt keys - 22mm crows foot socket - a bucket of patience Instructions Steps to follow: - Lift BMW e46 up safely. Use jaxle stands - Remove plastic engine under-tray (seven screws) so you can find all the bolts you drop through the engine bay. Leave the tray on the floor under the car to catch your mistakes - open bonnet and remove the following: Pollen filter housing and tray. Let t