joturbe

My 2000 Odyssey had the following codes read today at Autozone:

P0420
P1129
P1519
P0505

I found what the codes mean, but I need a little more detail. Are they related? For example if I replace the O2 sensors could this solve the cat converter error code and other problems? Thanks..

Fuse

p0420 failed cat, covered by an 8/80 so 8 years and 80k miles.
p1129 map problem, you want to diag? you have a volt meter?
p1519 iac problem, again you want to diag? you have a volt meter?
p0505 malfunction in idle system, same thing?


the cat code is on its own, the other 3 can be related to a possible vac leak, iac or map failure,idle adjustment,short or open in wires. To find a vac leak spray the intake and vac lines with carb or brake clean if you hit a spot and the rpms jump that would be you vac leak.

Again if you want to jump in we need a volt meter and some free time.

joturbe

The car has 200,000 miles, so we are out of warranty.
I do have a volt meter and would like to trace the problems down. I own an 1977 MG and love to track down electrical problems, but need some direction with a Honda.
I did notice when it idles it surges. Could this be the MAP sensor causing this?
You didn't mention O2 sensors as problems..Why not?
Where do we start?
Thanks for your direction..
John

Fuse

Nice ok lets start with the p1129 map.

Its one step by the book ok so you do not need and scan tool or honda hds just a volt meter. Do as it says get the car to operating temp. Keep it all plugged in (I use a safety pin jam it in the back of the connector) measure voltage at the red green wire of the map. It should be under 1.4 volts.

Let me know do not replace the map senser just yet.

And yes you might have a bad o2 we will get to that.

joturbe

Thanks for the documentation Fuse...a big help.

Here are the results:
the engine surges at idle so the voltage was not consistent, but it mostly stayed between 1.16 and 1.38. Occasionally it would jump to 1.40, but only a few times...voltage seemed to be affected by the fans coming on and off too. So I think we can safely assume that the MAP Sensor is working, right?
I just noticed on the Autozone web site that sensor is $68... I see a savings already!

step two?

Thank you--

Fuse

Nice good to see you back ya probably not MAP. Ok the diag for p1519 and
p0505 are about 30 steps of diag so lets just talk how the IAC (idle air control valve) works.

This is out of the book::::

Idle Control System Diagram
The idle speed of the engine is controlled by the idle air control (IAC) valve:

After the engine starts, the IAC valve opens for a certain amount of time. The amount of air is increased to raise the idle speed.

When the engine coolant temperature is low, the IAC valve is opened to obtain the proper fast idle speed. The amount of bypassed air is thus controlled in relation to engine coolant temperature.

Idle Air Control (IAC) Valve
To maintain proper idle speed, the IAC valve changes the amount of air bypassing the throttle body in response to an electrical signal from the PCM.

From me::::

Its a valve that controls the idle by bypassing air around the throttle plate. If the engine needs more rpm it opens a little if the engine needs less rpm it closes a little. Now we are talking 30rpms so you never feel this. If you look into your throttle body you will see an intake for the iac, turn the throttle you will see an exhaust port for the iac after the throttle plate. Now the iac has the capability of changing the idle from about 600rpms to about 1200rpms. So if it is malfunctioning it will kill your idle.

That said look at my pics.

Lets start with the electrical part of the iac (3 wires) the Yellow/Black should have 12volts with the key on connector pluged in. The Black should have less then .1 volts key on connector pluged in or connector un pluged 0 ohms good continuity to ground.

Get back with me. Safe bet p1129,p1519 and p0505 are all caused by a bad IAC but still lets diag to be shure.

joturbe

Hi,

Here are the IAC test results

the yellow/black had 12 volts with the key on and plugged in.
one black had 5.40 volts and the other had less than one volt (they both looked black anyway)

with the plug out, key on, both blacks registered .08 ohms.

Does this mean we have a bad IAC sensor since one of these has 5.4 volts registering?

Thank you.

Fuse

Ok so you say the black blue has 5.40 volts and the black has .08 ohms this is good . The black blue is the controller for the iac this just tells us the ecm is trying to operate the IAC.

I will give you the next two steps.

1. Spray your intake and all vac lines with brake clean. If you get to a vac line and the idle jumps up it means that vac line is leaking. Fix it.

2. Take off you IAC and look inside it for carbon sludge build up or it may just be stuck. Some time you can clean it out with what is called seafoam or sometime you just have to get a new one. Use a new throttle body gasket and IAC gasket so you do not create a vac leak and avoid taking off the throttle and cruise control cable thy are not to fun to re adjust. There are 4 bolts holding on the throttle body.There are two screws holding the IAC on and two coolant lines attached.

Let me know what you find just for all the future HANers. If you find nothing I have one odd ball idea or your IAC is stuck (if you find no sludge).

p0420 Is probably a failed cat you can get them cheaper at an exhaust shop
p1129,p1519,p0505 can all be caused by an IAC problem and or vac leak.

joturbe

Fuse,
Thanks, I'll give the IAC a cleanout and try the brake cleaner on the hoses.
To reset the Check Engine light, can I just unplug the battery for a few minutes, or will it have to be reset with a OBDII devise?

Thanks for all your help.
John

Fuse

Some time a battery un hook workes but then you need your radio code. I think you can just take it to an auto parts store have them pull it and reset it.