Monday 30 September 2019

E46 318i: Front-of-cat o2 / Lambda sensor replacement [Fault Code 271D, 271A, 271B] [Rear-of-cat 271C, 271F]

E46 failed its MOT on the O/S rear tyre and O2 emissions too high. I duly replaced both rear tyres with a new pair sourced through work for just £23 each and they are V-rated so should be ok for the Touring. As for the O2 level being too high, I was told this was a fault with an O2 / Lambda sensor so I plugged in a Snap On Modis scanner to see if this was right.

The code I got back was 271D, as in pic above, which is the up-stream or 'front-of-cat' sensor heating. Codes 271A and 271B show fault at the same sensor, but are labelled directly 'front-ofcat-sensor' with no heating suffix. This sensor is located slightly forward of the catalytic-convert mounted about halfway down the car's underside, as in the diagram below. The one shown to the rear of the cat is the down-stream or 'rear-of-cat' sensor. Code 271C applies to this rear sensor, along with 271E for Rear O2 sensor-heating. The two sensors, though essentially the same, are different parts and part numbers due to the rear sensor having a longer wire. [List of emission based fault-codes here.]

I got hold of a used sensor taken from another E46 318i from for £18. I prefer used OWM BMW parts that come with a warranty / guarantee over cheap spurious items. The least expensive spurious items start at about £20 for a sensor that can be used for either front or rear of cat, having a long wire than can be cut to length with two bare wire or universal wire-terminal ends that require the original plug to be soldered on from the broken sensor. On the other end of the spurious price range was Euro Car Parts, who offer an OEM-quality sensor for £68, which is pricey but comes with the correct wire-length and plug fitted.

My old sensor proved very tricky to remove with the car on fixed-ramps and I would not like to attempt it with jack and axle-stands. I was unable to crack the sensor off and unscrew it even with the use of special Lambda-sensor sockets and it began to round so I ended up booking ramp-time in the workshop of the company where I work and lifted the E46 Touring on a 2-post ramp to give loads of access underneath. To avoid the risk of breaking the Lambda-sockets or further rounding the sensor itself, I decided to cut about half of the sensor off using a 3.5" cutting-disc and used a 22mm deep impact-socket with a long breaker-bar to finally crack the sensor off. It was pretty seized on, but once cracked just unscrewed by hand. The replacement sensor screwed straight in and swapping / mounting the plug was easy to make for a 5-10-minute job once the car was positioned on the ramp legs.

The emission test result went from 2.2, with a maximum of 2.0 allowed, down to just 1.0 with the faulty sensor replaced. There is also a significant drop in neat-petrol smell emitting from the rear of the car when it is started from cold, so I'm glad this problem showed itself and got fixed.

Thursday 26 September 2019

BMW Common Emissions Error Codes / Fault Codes List 2711-273F [E46, E39 etc.]

2711-273F2740-27722773-279F27A0-27FF280A-29FF2A01-2CFF2D00-2FB7, CD87-CDAC,

2711 DMTL pump final stage
2712 DMTL magnetic valve control
2713 Oxygen sensors switched
2714 Oxygen sensor heater after cat. (bank2)
2715 Oxygen sensor heater before cat. (bank2)
2716 Controller heater sensor after cat
2717 Controller heater sensor after cat (Bank2)
2718 Speed (rpmsensor for missing tooth
2719 Speed (rpmsensor for periode timing
271A Oxygen sensor before cat.
271B Oxygen sensor before cat.
271C Oxygen sensor after cat.
271D Oxygen sensor heater before cat.
271E Oxygen sensor heater after cat.
271F Lambda sensor periode duration ageing
2720 Lambda sensor ageing TV
2721 Lambda sensor ageing after cat
2722 Oxygen sensor2 before cat.
2723 output heater O2-sensor before catalyst bank2
2724 Oxygen sensor2 after cat.
2725 Lambda sensor periode duration ageing bank2
2726 Lambda sensor ageing TV bank2
2727 Lambda sensor ageing after cat bank2
2728 Adaption multipl. area2
2729 Adaption multipl. area2 (bank2)
272A Adaption multipl. area1
272B Adaption multipl. area1 (bank1)
272C Adaption add. per time
272D Adaption add. per time (Bank2)
272E Adaption add. per ignition
272F Adaption add. per ignition bank2
2730 failure within the idle-speed control
2731 Camshaft control inlet - VANOS
2732 NW-Control of inlet B2 (8cyl)/outlet (4cyl)
2733 NW-KW synchronfailure
2734 TPS/MAF plausibility
2735 TPS/MAF plausibility bank2
2736 Throttle controller PWM short test
2737 EWS-manipulation control
2738 Catalytic-converter conversion
2739 Catalytic-converter conversion LSU
273A Catalytic-converter conversion LSU bank2
273B Throttle controller PWM long test
273C Throttle controller diff.
273D Catalytic-converter conversion (bank2)
273E Signal temper.sensor exhaust1
273F Signal temper.sensor exhaust2

This is originally from a thread on bimmerfest with a longer list of codes -