what is a Lambda? [Archive] - Bimmerfest - BMW Forums

: what is a Lambda?

12-01-2009, 07:08 PM
i have a 95 530i. it started to run rough (shake at stop or low rpm on highway) and i got the code 1222 Lambda Control 1. i dont know what a lambda is? has anyone had this code? what was your fix?

12-01-2009, 08:12 PM
Most likely your Oxygen sensor. That code can mean other things, but that is the most likely part.

12-02-2009, 04:24 AM
Lambda... 1/3 of a Nerd fraternity :dunno:

You can look up the codes on bmwe34.net but they do not get into the explination? I posted a link to it on this forum a couple of months ago. Here is another link that should be of more help, It is on the e30 but still should apply. This lists the Most common causes for code 1222.


12-02-2009, 04:33 PM
[QUOTE=CarDriver;4730964]Lambda... 1/3 of a Nerd fraternity :dunno:

Best Answer


12-03-2009, 08:08 PM
In an effort to collect more money from vehicle owners by boggling them, I believe the auto industry has substituted "lambda" for "oxygen" in describing the sensors... I guess it's working??

12-03-2009, 08:40 PM
Lambda = is an exhaust gas composition sensor to monitor chemical composition of exhaust gases especially NoX
(oxides of nitrogen )and feed data to the engine control system . Essentially , an oxygen sensor positioned in the exhaust pipe , so in all once the 02 sensor is replaced it should take care of your erratic idle problem .

12-03-2009, 11:28 PM
For a second there I thought I read "La Bamba" ... interesting term, oxygen sounds easier to remember!

12-05-2009, 10:09 AM
Lambda is a value (1) which relates to your air/fuel ratio ie how rich (below 1) or how lean (above 1). The Oxygen (lambda) sensor installed in your cat analyses the ratios of your exhaust gasses and the ECU makes the necessary adjustments. The Lambda setting of any particular car is a compromise between power and fuel economy and the ideal value is taken to be 1 (14.7:1).

attack eagle
12-06-2009, 04:36 AM
oxygen sensors don't read air fuel ratios...

they read lambda (stoich), so at when reading STOICH which is 9:1 for alky, and 14.7:1 for gasoline, your wideband sensor will read alcohol's stoich as 14.7 on the gauge.
From wiki
The sensor does not actually measure oxygen concentration, but rather the amount of oxygen needed to completely oxidize any remaining combustibles in the exhaust gas. Rich mixture causes an oxygen demand. This demand causes a voltage to build up, due to transportation of oxygen ions through the sensor layer. Lean mixture causes low voltage, since there is an oxygen excess.

12-06-2009, 05:01 AM
http://www.dtmpower.com/Exhaust%20Gas%20Analysis%20with%20Lambda%20Sensor. pdf