But, again, long driving does nothing for secondary air. 300 - 400 miles is plenty of driving to get all the monitors set.

As I said SAS will set in 2, maybe 3, cold starts. My extent of using them is to order tires from and having PB mount/balance them. Frankly, I wouldn't let Manny, Moe or Jack near any of my cars. If it doesn't come ready that start, it won't try again until the engine is cold. The computer only 'checks' at cold start. The Secondary Air monitor should set in just a couple cold starts. The Cat monitors set very quickly after that, too. In my case, one appeared to be older than the other, so I replaced the older one and the problem went away immediately. If you've passed all these simple tests, then it's one of the upstream O2 sensors. If not, you have a bad relay valve at the back of the intake or a cracked/broken vacuum hose somewhere. Attach a vacuum reader to the hose and start the engine. Next, with cold engine, connect the air pump to the valve and disconnect the vacuum hose from the valve. You'll be able to tell because you'll hear the engine noise from the valve change tone. Then, using a MityVac, or equivalent, apply vacuum to the vacuum nipple. Next, at any engine temperature, disconnect the air pump and the vacuum hose from the secondary air valve. From a cold start, have your air pump hose disconnected from the valve and see that it puts out a strong stream of air. So, to correct, first make sure your pump is working. If the sensor is 'lazy' the O2 monitors will eventually come ready but the SAS will never set because the computer can't see this slight, rapid, voltage fluctuation as the air come on. I found that the upstream sensors are looking for a slight voltage drop when the air pump kicks in. When bringing my OBD II monitors to ready, the Cat monitor took a long time to set, and the secondary air never would. I found a wonderful article on e46fanatics, I think.Īnyway, the upshot is that you probably have a 'lazy' O2 sensor. I had a similar problem with my '02 money pit, err, 525i.

Secondary air system not ready mercedes