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[Albatross]

0170 & 0173

I used to get the old chestnut 0420 code and then moved the secondary lambda sensors to behind the main CATs which has resolved that, but now I have the 0170 & 0173.

Why? Are these for the front lambda sensors or something?

What do I try now?

[VXL V6]

Fuel Trim

I wonder if the block learn values need resetting now you've moved those sensors?  :-/

Regardless, the block learn values should 'learn' over time anyway.

[VXL V6]

Incidently did you have those codes before you moved the lambdas and have you replaced them with new ones?

[Albatross]

No, I had 0420 and 0430 before. That code cleared when I moved the secondary (further back pair) lambda sensors back behind the main cats rather than between the pre-cats and the main cats.

I had to replace one of the lambda sensors as it was rusted into the thread so I just left it in there and cut the wire and put a new one into the new boss behind the main cat when I had the custom "cat-back" exhaust made.

[VXL V6]

Fuel trim codes are generated when the ECU can't compensate the fuel / air ratio against the readings the Lambdas are giving.

When are the codes generated? Cold start or normal operating temperature?

Best person to speak to would be Kevin Wood.

[Albatross]

Fuel trim codes are generated when the ECU can't compensate the fuel / air ratio against the readings the Lambdas are giving.

When are the codes generated? Cold start or normal operating temperature?

Best person to speak to would be Kevin Wood.

Thanks Andy; I've sent him a PM, let's see what advice he can add.

[VXL V6]

You can call me James if you like but my name is actually Andy!!!!!!  

[Kevin Wood]

Fuel trim should be unrelated to the second lambda sensors as only the pre-cat lambda sensors have an influence on this, or so I believe. :-/ You never know..

Does anyone have the actual definition of these error codes?

Kevin

[Albatross]

I don't have the true definition, but I'm told they're to do with fuel trim.

There's a bit of history to this one...

I used to get 0420 & 0430 which was a notification that the difference between the readings at the 1st lambda sensor and the 2nd was not cleaned enough which indicated that the "pre-cats" were a bit tired. This is very common on the 2.6 and 3.2 litre engines.

I then had a stainless (quiet) cat-back exhaust made and whilst they built it thay added 2 new lambda sensor bosses behind the main cats and moved the secondary sensors further back so that both the pre-cat and the main cats were cleaning the air between the two sensors on both sides.

This has cured the 0420 & 0430 codes which is some success, but now I'm getting these two new codes 0170 & 0173. Someone (above) has said that this is to do with lambda sensor or fuel trim issues, and after doing a search on here on "0173" I have seen evidence to confirm, but I'm now a bit lost. :-/

[Albatross]

Kevin,

You have a PM

[Marks DTM Calib]

Question.......did the new codes appear immediately after the work was done or some time after?

The definitions are as follows:

 P0170 - Fuel trim malfunction (Bank 1)  
 P0173 - Fuel trim malfunction (Bank 2)  

Now, this can be affected by the exhaust!

Also, worth checking fuel filter, inlet system for airleaks etc.

[Albatross]

Question.......did the new codes appear immediately after the work was done or some time after?

The definitions are as follows:

 P0170 - Fuel trim malfunction (Bank 1)  
 P0173 - Fuel trim malfunction (Bank 2)  

Now, this can be affected by the exhaust!

Also, worth checking fuel filter, inlet system for airleaks etc.

Did the new codes appear immediately after the work was done or some time after?

I'm not sure, but the new exhaust hasn't been on that long (2 months) so I'd consider "some time after" to be as good as immediate. I don't know how long the error message has been ther because my EML buld went IMMEDIATELY when the exhaust was changed and lambda sensors moved and I only became aware when the "service" light showed for a while.

Now, this can be affected by the exhaust!

Bugger.

Are there any other symptoms or ways of checking?

[Kevin Wood]

I would say it's worth getting a Tech 2 or a ELM code reader on it and having a look at the live data, specifically the fuel trim values, and lambda sensor behaviour, to see what's going on.

The new exhaust could be affecting the fuel trims by virtue of being more or less free-flowing but I wouldn't expect it to be significant enough to put the EML on. If there are air leaks upstream of the main lambda sensors, or induction air leaks, fuel system problems, etc. this would be much more significant. That this occurred exactly when the exhaust was changed is a bit of a coincidence but if the fuel trims were already just below the limits maybe the slight effect the new exhaust had has pushed them over the limits.

The fact that both banks are complaining makes me think it's something common to both - fuel supply or air leaks.

I wouldn't expect this to be related to the post-cat lambda sensor relocation because they have no input to the fuel trim, they are for monitoring cat performance only.

Kevin

[Albatross]

Very useful thanks.

I have to go to Bicester this afternoon, so I wonder if TB is around and prepared to plug in and give it a once over?

I'll drop him a PM too to see if he is able.

Thanks

Nathan

[TheBoy]

Very useful thanks.

I have to go to Bicester this afternoon, so I wonder if TB is around and prepared to plug in and give it a once over?

I'll drop him a PM too to see if he is able.

Thanks

Nathan

yes, I'm in all day.