• Welcome to H4O! For a reduced ad experience, please login or register with the forum.

Bought my first hummer (H3) and it’s unfortunately throwing a few codes. Looking for advice/tips you all might have.


Probationary Member
New York
So I was fortunate enough (if you could say that) to be driving by a an old man putting a for sale sign in front of his 2006 hummer H3. We settled for $6000. It has 83k miles on it. Clean title, with extensive maintenance records (shown on carfax) and has never seen winter. Undercarriage is spotless. He unfortunately was having health issues (83 yrs old) and just no longer had time for all his “toys” (his home was well into the million dollar range). So I don’t think money was an issue for him.

However it did have a check engine light on and is throwing a few codes. He was open about it and I ran a scanner before buying it. I’m rather handy and would like to see if I can fix any of this myself.

P0446 EVAP Vent Solenoid Valve Control System

C0186 Lateral Accelerometer Circuit Malfunction

C0196 Yaw Rate Circuit Malfunction

C0240 EBCM Malfunction

He has receipts from August 2022 that show he replaced the vent solenoid ($300 part and $200 in labor, crazy). Along with $1300 for a new radiator.

Aside from the Evap code others seem to be from the ABS and from what I saw on this site could be related to bad drainage in the sunroof ultimately flooding the sensor under the front seat.

Was just wondering if any one had any insight or tips. I have a trusted mechanic but he’s a master mechanic with Ford. He’s coming over this week and I’d like to be able to pass anything I can’t do onto him but share some knowledge.

Or if someone could possibly point me to a few good videos on what to fix. It’s up on it fluids changes, though I’ve changed the oil just in case, and I’m going to replace the spark plugs next week.


El Diablo
Staff member
Welcome to H4O!

For P0446, I'd start with a new gas cap and OEM is pretty much always better than aftermarket for some of these things. Also, if that part was replaced in 2022, I would check that too. Maybe a defective part, maybe not installed correctly.

Sometimes when there are multiple codes like this, and some of them seeming unrelated, it may point to a BCM issue. The BC is located in the kick panel in the passenger footwell. It can be damaged by water, including from sunroof drains. Sometimes you'll see these codes change when it's a BCM issue, like erratic or inconsistent issues. Assuming it's driving okay, I would drive some more and keep checking codes.

Also, we'll always tell you to make sure you have a good battery, good strong and tight battery terminals, and no corrosion on those terminals or in those cables. As you're in the rust belt, check for good connections on the grounds and clean them up as needed.


Well-Known Member
Battery cables. Multiple codes is often a result of a bad ground. The cable ends (especially in 06-07) are notorious. Might not be the issue but if it has factory clamps…they are now 15+ years old. They sucked when they were brand new! Regardless of the codes…probably the easiest and cheapest upgrade you can do is to get some good clamps on the cables.