Emissions system help requested - p0810 p0814 - O2 sensors?
Typically it was P0810 and P0814 which are constant, and p0410, p0420 and p0745 show up periodically.
I have already replace the emissions hard line tubing which was cracking.
The pump works, and I know the air is making it into the engine as on cold start (or random test run of the Secondary Air Injection system), the engine idles at around 1k for 30 seconds before dropping back down to normal idle.
I did replace the check valve as well to be safe, although I suspect that was not it, but it was covered in crud and the intake filter was blocked.
I started with the cheapest parts and am working my way up, as the diverter valves are $250+ each.
That leaves the O2 sensors which are not exactly cheap either. At 96k they are probably due for replacement since Bosch recommends they be replaced at 100k miles.
But I want to make sure that I am reading the sensors right, the ones after the cats should be steady in voltage at idle once the engine is warmed up, the ones in front should constantly be changing between 0.1 and 0.9V correct?
I have a snapshot of mine over a few min period, the 2 prior to cats fluctuate with similar values, the ones after the cats, the left side is static (or mostly static) in voltage, the right one fluctuates wildly, similar to the precat ones.
I'm guessin the right post cat one is the one failing, and needs to be replaced in the interim to get rid of the problem..
Or could it be something else.







Well it was a problem before that I had fixed but seemed the fix did not work long enough. It is a shaft that comes from a vacuum pump "thingy" to a ball that is connected to a valve inside the intake that has got something to do with vacuum and air. The ball connected to the valve on the front of the intake is worn and the shaft comes off. Last time i fixed it with cable ties and it was fine till now but it probably stopped working properly as the cable ties must've created more friction for the shaft to move less freely. So I loosened the vacuum thingy and squeezed the ball clip with pliers to make it smaller therefore to clip on tighter. Deleted the faulted codes and started her up and she's fine again. Don't think this is going to last long either but I will just look for the part number and order a new vacuum thingy with a shaft that clips on securely. If its the ball that is worn I am going to drill a hole through both and put a shaft through with circlips on either side. Not removing the whole intake just for that.
The ball with the ball clip shaft attached.
The vacuum thingy.
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Did you get that part #? My C300 is throwing these same codes at me. Hopefully I can have a fix as easy as you said - I'd rather just replace the whole part if possible. I've been fighting this thing for years, bringing it to multiple shops who can't figure it out - if it's this simple, I'll be blown away!



Did you get that part #? My C300 is throwing these same codes at me. Hopefully I can have a fix as easy as you said - I'd rather just replace the whole part if possible. I've been fighting this thing for years, bringing it to multiple shops who can't figure it out - if it's this simple, I'll be blown away!

Well it was a problem before that I had fixed but seemed the fix did not work long enough. It is a shaft that comes from a vacuum pump "thingy" to a ball that is connected to a valve inside the intake that has got something to do with vacuum and air. The ball connected to the valve on the front of the intake is worn and the shaft comes off. Last time i fixed it with cable ties and it was fine till now but it probably stopped working properly as the cable ties must've created more friction for the shaft to move less freely. So I loosened the vacuum thingy and squeezed the ball clip with pliers to make it smaller therefore to clip on tighter. Deleted the faulted codes and started her up and she's fine again. Don't think this is going to last long either but I will just look for the part number and order a new vacuum thingy with a shaft that clips on securely. If its the ball that is worn I am going to drill a hole through both and put a shaft through with circlips on either side. Not removing the whole intake just for that.
The ball with the ball clip shaft attached.
The vacuum thingy.
Last edited by Robert L; May 17, 2021 at 04:26 AM.




