code question

[garllo]

Hello Gents,
I have been getting an occasional code in my'98 coupe. DIC says
PO410 HC . The book says "Air system" Anyone have a more specific idea or experience?

[ToolGuy]

Stuck air injection check valves, bound up air pump, electrical fuse or the power relay going to it are many causes for this code. However yours is occasional, so I would say the power and relay going to it are fine.

If you hear the humming from the drivers front headlamp on cold start, you may have lost your relay for the solenoid.

The key is whether the pump is running at the first start up in the morning.
It may run for only 2 mins maximum depending on outside temperature.

[garllo]

The pump does run at cold start but I am not sur how long. Have to check. It may be coincidental but this started after I blew out the engine compartment w/compressed air (part of my annual cleanup)? Thanks Tool Guy for your response!!

[garllo]

Here is an update- I replaced the drivers side check valve figuring that it was cheap and easy to do and that would take that valve out of the equation. I took a long ride yesterday and the check engine light came on twice, hours apart . The first time was P0410 HC so that may have been in history but the second time was a new incident (still P0410). Both times occured when the engine was hot after having run 30 to 40 miles. As I have said before , I can hear the pump running at start up and it winds down and shuts off after about 1.5mins. I have read about cleaning the check valves etc but this code seems to indicate a problem with the system? Could this be an indication of a failing O2 sensor ? Any other ideas? By the way , the car runs great-no issues with driveability or performance!!

[c4c5specialist]

HI there,

I would be checking to see if your vacuum solenoid is opening.

Remember, if that does not open, you will NOT have correct function.

Allthebest, c4c5

[RH Factor]

I'd check the vacuum hose from the solenoid to the air pump. It's a plastic line and is prone to cracking.[It's gross, but an easy way to find a leak is to blow cigarette smoke through the line.] Good luck!!!!

[sodian]

I had the same problem with mine a few years ago. I believe the check valve on the passenger side was the problem.

[garllo]

Thanks to everyone for your help. I haven't had a chance to get back here for a while but I'm back now and I have solved the problem with the AIR system. As it turns out , the electric relays were bad. I think that they were not working properly once the engine compartment got hot. I had read that the pcm does a test that runs the AIR pump and the O2 sensors measure a difference once the engine is at temp and I don't think that the pump was coming on and here's the real hoot. I came to this conclusion because my horn would not work or work intermitantly once the car was hot. I narrowed it down to the relay ,(code stated "horn relay circuit) replaced it and never had a problem again! Thanks again guys as always for your help! This forum is a great tool to have in your box.

[SG Lou]

Originally Posted by garllo

this forum is a great tool to have in your box.

amen to that !