Hello everyone in getting these codes and would appreciate your advice on them. I've done the translation in codes since I have a generic scanner.

ECM-432B
ECM-223B
ECM-433B

On this next one I'm not sure if it's ECM-1210 or ECM-121B but this is what my generic reader reads.

Mass or Volume Air Flow A Circuit Range/Performance

Also a quick question about the oxygen sensors, where can I find the different locations/banks? I couldn't find anything in Vida but in probably just missing it.

I would just like to know where everyone thinks I should start with these codes my vehicles throwing. Have a great weekend everyone. Thanks for your time!

 

What model of XC90 do you have? 5, 6 or 8 cylinder? This will make a difference on which bank you are referring to.

 

It is the 5 cylinder

 

The 5 cylinder has only one 'bank' so the issue could be anywhere in the intake system. Lets go with your DTCs.

ECM-432B + ECM433B relate to your leakage diagnostic pump. Probably need to check the wiring and possibly replace the pump.

ECM-223B relates to the rear O2 sensor signal missing. This will need some diagnostic but you could monitor it on your generic reader (assuming it displays data also). It should be around 0.6v-0.7v while hot and driving along.

ECM-1210 or ECM-121B really need to be defined since they are either flow to high or low. This would lead us to the MAF to check but could be another issue elsewhere. Can you determine if it is one or the other? Does your reader define flow too high or low?


I would suggest driving, get the vehicle hot then monitor the rear O2 and see what it says. From there we might get a direction.

 

Thanks for the reply, I will try driving it tomorrow and getting the data. Is there anyway I can tell if the MAF is too high or too low with data on my scanner? I didn't know if there some type of range for it also?

 

There lies the issue. The MAF value changes at different load, engine speeds, throttle angles etc. so it is difficult to give a definitive answer. I believe the spec is 12-16 kg/hr at idle, warm with the AC off. So, depending on your scanners units of measure, this may or may not agree with your scanner.

If you look at the short term fuel trim you could see whether it is adding or subtracting fuel and that could be a clue. The adaptive should start at 0 and then add or subtract fuel based on sensor input so if the sensor (MAF) is inputting a high value, the ECM will add a lot of fuel and because the actual amount of air is lower. Then the mixture going past the O2 sensor will be rich so the short term fuel trim will be negative as the ECM tries to reduce fuel to correct the mixture.

Conversely, if the MAF is inputting a low value then the actual air fuel ratio will be lean and the short term trim will try and add fuel.


If they are +/- 5% I would not worry but more would be a cause for concern

Good luck.

 

I'm going to attach my data collected from my scanner. It appears to me that my oxygen sensor isn't putting out enough voltage. Please let me know what you think. Thanks,Have a good one!

 

I would agree. But, you have to think in terms that the O2 sensor is telling you the exhaust is lean so you may have an exhaust leak before the O2 allowing oxygen into the exhaust and causing the O2 to read lean. Looks like you have a P0420 DTC in addition to everything else.

 

What would the first thing you would do? Probably check for exhaust leak. I'm just wondering where to go from there if there isn't a leak. It has close to 200,000 miles on it so I'm sure it could need a catalytic converter or an oxygen sensor but if like to rule things out. Thanks again!

 

before replacing O2 sensors or MAFs, check for vacuum leaks. You can also try cleaning the MAF with CRC spray to see if that helps. You may need to get a shop to do a smoke test to find some of the more obscure leaks - but in the 5 cyls there some common culprits - (ie the vacuum tree and an elbow under the intake manifold near #1 that goes into the PCV plumbing).

 

Just alittle update, I did clean the MAF today then cleared the codes. The ! mark engine message problem has went away which I believe it came on when I started getting the MAF code. I've started it up 4 times since I did this. The 2nd time the check engine light did come back on. All codes minus the MAF code. I plan on tackling the other issues another day. I'm hoping that cleaning the MAF has eliminated that other code but only time will tell. Thanks and I'll keep you updated!

 

All codes are back so I guess the cleaning of the MAF didn't help the problems I was having. I'd like to get back to checking out more things but the Missouri weather has turned back to winter. I will continue to keep you updated when I'm able to get some things done.

 

Its been awhile but I do have some updates. I did replace the leak diagnostic pump and that did not fix my problem. Below is attached is the +/- of my short term fuel. Your advice moving forward on what I need to do next is greatly appreciated.

 

How are you driving in the first part of your graphing picture? Accelerating? When the large spike goes positive have you closed the throttle? Most of your adaptive data is negative so it suggests your MAF is reading high so the ECM is being told there is more air being consumed by the engine than is actual. When it adds the amount of fuel it thinks is correct, the mixture is too rich so it has to take fuel away from its calculation. This would rule out an air leak as the MAF value would be lower causing the ECM to add fuel. Your fuel pressure may be too high allowing too much fuel into the engine (as the injectors are manipulated by time) so a higher pressure would allow a greater volume to pass in the same time frame. You could try to introduce a small air leak (like removing an EVAP hose or similar) which would allow unmetered air into the system and when the fuel was added, the end result may be a more accurate mixture. Drive and look at your front oxygen sensor. It should alternate between 0.99 and 1.01. If it spends more time above 1 then the mixture is lean and if it is below 1 then the mixture is rich. Try and keep the throttle steady for a while and see what the sensor is doing as this can give you an idea of rich or lean. Give us an update.

 

Most of the driving was done around town, stop and go. The 3 frames where the spikes happen. It went from 0 mph to 10 and then to 7. I really appreciate the detailed instructions, I will do those when I get time. I just wanted to update you with this other information.

 

__________________________________________________ ______________

Results after introducing small air leak

1. 1.015
2. .967
3. .986
4. 1.051
5. .992
6. .988
7. 1.016
8. .996
9. 1.003
10. 1.078
11. 1.009
12. .951
13. 1.041
14. .977
15. 1.010
16. 1.011
17. 1.023
18. .997
19. .992
20. 1.033

 

Any ideas on what direction I should look into going next to get this problem resolved?

 

My results show more above 1 so I guess it's running lean? What would this recommend doing to fix the problem?

 

alright, I now have a Dice scanner, what info do I need to be most beneficial for you to help me determine what is going on with my vehicle? Thank You.