Rodeo PO174 Code

[tonytwotime]

Hi guys. Autozone gave me a PO174 diagnostic readout. I did some searching, but I haven't found the exact same readout, as mine. I know everyone says it's rarely the O2 sensor, but I got FAILED H02S21 (heated oxygen sensor - bank 2 sensor 1). I could be wrong, but that means the sensor completely failed, right?

Here's the entire readout: (autozone)

Definition:
Fuel trim bank two condition
Explanation:
The ECM has detected a rich/lean air fuel ration
condition on engine bank two
Probable Cause:
1. If bank one and two are set together, (don't know what that means) suspect a fuel pressure condition or MAF Sensor
2.FAILED H02S21 (heated oxygen sensor - bank 2 sensor 1)
3. Ignition Misfire Condition
4. Fuel Injector Problem
5. Engine Mechanical Condition

I went ahead and got the bosch oxygen sensor being I was there, but haven't installed it yet. (It was $53.99 - just FYI, or for future readers)

Let me know what you guys think.

Anthony, Delaware
2002 Isuzu Rodeo
39K Miles
Out of Warranty
No Previous Problems

[XR400R]

PO174 is an Isuzu code indicating a lean mixture condition on bank 2, which is drivers side bank. Due to the importance of the O2 sensor in the closed-loop feedback fuel control system, it is entirely possible the O2 sensor is the problem. Since you have the sensor, why not change it & see?

39K miles on an '02? Surely that is not the total milage on the veh? In my limited experience (40 yrs shade-tree wrenching - long before O2 sensors existed), it is very rare for O2 sensor to fail after only 39K miles. Unless they've been poisoned, hit or otherwise abused. I've had em last 250K miles. I usually change em at 100k whether the need it or not. A fresh O2 sensor will frequently improve runability and fuel milage, in my experience. Just my opinion anyhow.

[tonytwotime]

Im going to change it, I just got tired of messing with it, and found this forum. I figured I would post and see what everyone thought.

Yes, 39K is the total mileage on the vehicle. It's my "go to" vehicle. I have a couple others that I bum around town in, and do most of my driving in. My Rodeo for "better" occasions. It's in great condition, and has been babied. I'm adding a grille guard, and getting rims and new tires in the next 6 months or so. It doesn't NEED it, but I want to do it.

We just had 2 feet of snow in delaware, and this problem popped up during this time.

Thanks for the reply.

[tonytwotime]

Well, that wasn't it. It hasn't stalled, but the check engine light is still blinking. It still starts kind of hard also.

What do you think I should check next?

[Cat Fuzz]

Check for vacuum leaks on the engine side of the MAF sensor. A leaking PCV hose, vacuum hose or intake manifold gasket can cause this code to pop-up. Also, stop driving the truck. The flashing CEL indicates a catalyst damaging misfire. You could end up having to replace your catalytic converter. Also, properly cleaning the MAF could also fix this. This needs to be done carefully and properly or damage could result.

[tonytwotime]

Thanks. Whats the best way to check for leaks in the hoses? I hear spraying carb cleaner on the intake manifold gasket would help to find if that is faulty. I also found maf cleaner today. No idea about the hoses though.

[Cat Fuzz]

Be very careful with the carb cleaner. I've had it ignite on me before while doing that. Hoses can usually be visually inspected. Look for cracked hoses or ones that fit very loosely. Also, check the clamps that hold the air intake in place.

[tonytwotime]

Another question, if you don't mind. Where is the maf sensor, exactly? I found the spark plugs, which are buried inside the engine. That surprised me.

I hear replacing the O2 sensor might end up being a big mistake, as 2002 3.2L rodeos use "special" O2 sensors. I also hear of people blowing out their heaters, because of the change.

Also, was the manifold intake gasket a recall on 2002 rodeos? My friend said he had an 02', and it was recalled for something, but he couldn't remember for what.

[tonytwotime]

I forgot to add I also got a new PO155 today. I borrowed a diagnostic device from a friend.

[XR400R]

I thought you replaced the pre-cat O2 sensor on drivers side? The PO155 code indicates the internal heater in the drivers side O2 sensor has failed. Sensors have an internal heater to get the engine into closed-loop operation faster & reduce emissions.

It is absolutely not true that you need to use some sort of fancy, expensive O2 sensor in the Isuzu 3.2. I replaced both pre-cat sensors in mine a year ago with $26 universal O2 sensors I got from Rock Auto (Standard Part# SG450) and they work perfectly! All O2 sensors do pretty much the same thing. Since the ones I installed were universal sensors, I had to cut the harness connectors off the old OEM Denso sensors & solder them onto the Standard sensor. But other than that, piece of cake.

Also, the MAF is part #3 in this diagram of the airbox. It can be cleaned with MAF Sensor Cleaner made by CRC (at any auto parts store) if you are VERY careful. The three sensor wires within it are very delecate! That may or may not bring back its efficiency. Worked for me.

The only IMG recall I'm aware of on 2nd gen Rodeos/Passports was not really a recall, only a TSB. It changed the torque on IMG bolts from the original 17 ft/lbs OEM-specified torque, to 13 ft/lbs because so many OMG failures were being reported due to over-torqued/crushed intake manifold gaskets.

You really need a manual if you're going to be working on this veh. I have one on RapidShare for someone else & I think I have some downloads left. If you'd like a copy, let me know & I'll pm you the RapidShare link to it. Warning- it is a huge .pdf file!

[tonytwotime]

Sensor was changed, but the error is still there. Actually, the PO155 is new, and the sensor was changed because of the PO174 code.

Send over that manual. anthony2610(at)gmail.com I'll pm you too.

I saw a post from some guy claiming he had to spend $120 per sensor, because rodeos needed, as I said, "special" sensors. Thanks for clearing that up.

It's also iding at 2-2500 rpm's, which is new also. Swings from under 1,000 to 2,500, and back again, until I put it in gear.

[XR400R]

Darn, that's a conundrum for sure! You sure the IMG is OK?

PM sent.

[tonytwotime]

Not sure what is ok, and what isn't, at this point. I'm going to test the replaced O2 sensor, to see if I got a lemon. Highly unlikely I imagine, but the way things are going for me lately, I wouldn't doubt it. Have you had trouble removing the O2 sensors? I had to buy a breaker bar, with an O2 sensor socket, to get the damn thing off.

Intake manifold gasket is next, I guess. I probably should have started with this, after what I've read from other rodeo owners, and PO174 codes.

[XR400R]

Originally Posted by tonytwotime

Not sure what is ok, and what isn't, at this point. I'm going to test the replaced O2 sensor, to see if I got a lemon. Highly unlikely I imagine, but the way things are going for me lately, I wouldn't doubt it. Have you had trouble removing the O2 sensors? I had to buy a breaker bar, with an O2 sensor socket, to get the damn thing off.

Intake manifold gasket is next, I guess. I probably should have started with this, after what I've read from other rodeo owners, and PO174 codes.

No, I've never had any trouble removing an O2 sensor on this vehicle, or any other. Probably because I replaced either OEM-installed sensors, or those installed by me and I ALWAYS use plenty of anti-sieze at install. Even though most sensors come with a dab on them, I usually wipe it off & add my own to be sure it's quality goop & there's enough.

I've never experienced an IMG failure, but based on what I've read elsewhere, that's the first thing I'd suspect based on all of your descriptions & actions so far. I did replace my IMG when I replaced the buried thermostat at about 100K. Whatta pain! Guess I can't complain. The OEM thermostat lasted 100K! And it never did fail, I just replaced it cause I was afraid it would soon.

[tonytwotime]

Autozone is telling me that the IMG is a 3 part installation. Apparently, its 3 different gaskets? When you guys say, "intake manifold gasket", do you mean just the one on top? He also said it's not an easy process....