D16Y8 CEL codes issue: P0170, P0171

[ToTo17]

Hey so I have this check engine light that has been on for a while even after car repair shop fixed the exhaust leak and smog. The light came back on and was wondering if it might be an faulty ecu since their is no vacuum leak or exhaust leak and anything indicating that my car is running lean. I have a photo of the ecu and was also wondering what the blue wire is?

 

[ToTo17]

The only problem with that is I know what the code is already because my car is an ODB2 not ODB1. The code my car is throwing is a p0170 and 171 but already repaired those issues.

 

[ToTo17]

That's why I'm saying it's a faulty ecu and probably just need to replace it.

 

[buzzbombtom]

Doubt its the ECU . If it HAD the exact problem that the garage fixed, then it came back AFTER said repair, it was not fixed.

 

[ToTo17]

What is it then because there are no vacuum leaks, map sensor replaced, all gaskets changed, no exhaust leak pretty much every possible lean code fix has been done.

 

[HeX]

Im a bit particular about troubleshooting CEL codes, so lets get some basics out of the way...

P0170 - Fuel Trim Malfunction Bank 1: http://www.engine-codes.com/p0170.html
P0171 - Fuel Injection System Too Lean Bank 1: http://www.autocodes.com/p0171_honda.html

What is it then because there are no vacuum leaks, map sensor replaced, all gaskets changed, no exhaust leak pretty much every possible lean code fix has been done.

Are you only going by what the shop told you or have you personally inspected each vacuum hoses? If not the do so because it possible that the shop did not properly do their due diligence.

Besides that, if you read through the links I provided you will see that vacuum leaks are not the main culprits of either code, although that doesnt rule them out entirely. Therefore, inspect and possibly clean the Mass Airflow sensor and inspect the top O2 sensor then try to identify the brand, which is usually imprinted on the housing. If its anything but NTK then thats likely the problem and you need an NTK O2 sensor because Hondas are very finnicky about these parts.

Its extremely unlikely that your ECU is the issue especially if the car is otherwise running fine. These are simple CEL codes to deal with anyways.

 

[XpL0d3r]

@ToTo17 get the blink codes, as @ctag mentioned. Reason being, the Civic does not actually have a P0170 code, and this can be confirmed by checking out the list HERE. Notice that the codes in the list go from P0141 to P0171, omitting anything in the middle, including P0170 which is what you're reading. Get the blink codes and compare them to the list on the first post in that page, this should help you out.

By any chance, do you have a K&N air filter? An oiled filter, not a dry one. Those can cause problems similar to what you're getting.

As others have said, your ECU is probably fine.

 

[HeX]

...By any chance, do you have a K&N air filter? An oiled filter, not a dry one. Those can cause problems similar to what you're getting...

It seems to be a common miscommunication that any oiled filter can cause an issue when its actually the EXCESSIVE saturation of the oil on K&N air filter. The extra oil can drip loose and makes its way into faulting sensors. If this is the case for you, @ToTo17 , then I would suggest to simply clean the filter then mildly oil it and let it soak in before installing it, which is what K&N instructions suggest as I recall.

 

[XpL0d3r]

It seems to be a common miscommunication that any oiled filter can cause an issue when its actually the EXCESSIVE saturation of the oil on K&N air filter. The extra oil can drip loose and makes its way into faulting sensors. If this is the case for you, @ToTo17 , then I would suggest to simply clean the filter then mildly oil it and let it soak in before installing it, which is what K&N instructions suggest as I recall.

Yeah, I've heard a few stories where the filter had too-much oil right out of the box. Personally I have a K&N oiled filter and it's been great for me. But yeah, any oiled air filter is subject to problems if too much oil, not K&N specially.

 

[ToTo17]

So I have a Injen Short Ram Intake that is smog legal for my car only and has a 3" Injen filter. I have recently replaced the top O2 sensor with a
Denso 234-4099 Oxygen Sensor or https://www.amazon.com/gp/product/B000C5WCN6/ref=oh_aui_detailpage_o06_s00?ie=UTF8&psc=1
Honda's actually do have a P0170 and P0171 codes especially for an ODB2 98 Civic EX. I have an ODB2 Scanner tool which is how I am getting the codes. My honda also does not have an MAF sensor but a MAP sensor but 8th gen civics have an MAF sensor. Also me and my mechancial personally checked for vacuum hose leaks and there were none otherwise we could hear it too. There was an exhuast leak between the manifold. We changed the gasket on that and no more exhaust leak. All gaskets were replaced with new ones. As for the oiled filter not so sure about that because mine isn't K&N but Injen.
@XpL0d3r @HeX

 

[XpL0d3r]

So I have a Injen Short Ram Intake that is smog legal for my car only and has a 3" Injen filter. I have recently replaced the top O2 sensor with a
Denso 234-4099 Oxygen Sensor or https://www.amazon.com/gp/product/B000C5WCN6/ref=oh_aui_detailpage_o06_s00?ie=UTF8&psc=1
Honda's actually do have a P0170 and P0171 codes especially for an ODB2 98 Civic EX. I have an ODB2 Scanner tool which is how I am getting the codes. My honda also does not have an MAF sensor but a MAP sensor but 8th gen civics have an MAF sensor. Also me and my mechancial personally checked for vacuum hose leaks and there were none otherwise we could hear it too. There was an exhuast leak between the manifold. We changed the gasket on that and no more exhaust leak. All gaskets were replaced with new ones. As for the oiled filter not so sure about that because mine isn't K&N but Injen.
@XpL0d3r @HeX

The code scanner may be reporting it incorrectly.
http://www.civicforums.com/forums/183-6th-generation-civic/354392-honda-civic-98-p0170-p0171.html

Just jump the service connector and get the blinking codes, what can it hurt?

Is it a paper air filter? If so, it's not oil.


Sent from my iPhone using Tapatalk

 

[ToTo17]

Here's the air filter http://www.procivic.com/pages-product_car_part_info/category-70_85/product-304/index.html
and got the codes tested from multiple scanner tools as well as the shop.

Well now it's throwing a P0133 lol because I haven't checked it in over a couple of weeks since the other codes. @XpL0d3r

 

[HeX]

P0170 - Fuel Trim Malfunction Bank 1: http://www.engine-codes.com/p0170.html
P0171 - Fuel Injection System Too Lean Bank 1: http://www.autocodes.com/p0171_honda.html

P0133 - Oxygen Sensor Circuit Slow Response, Bank1, Sensor1 (http://www.obd-codes.com/p0133)

Thats 3 codes all pertaining to the top O2 sensor. Need anything say more?

 

[ToTo17]

Well I just replaced it a couple weeks ago with the Denso 234-4099 Oxygen Sensor or
https://www.amazon.com/gp/product/B000C5WCN6/ref=oh_aui_detailpage_o06_s00?ie=UTF8&psc=1
@HeX

 

[HeX]

Well I just replaced it a couple weeks ago with the Denso 234-4099 Oxygen Sensor

Perhaps you missed what I wrote earlier.

... inspect and possibly clean the Mass Airflow sensor and inspect the top O2 sensor then try to identify the brand, which is usually imprinted on the housing. If its anything but NTK then thats likely the problem and you need an NTK O2 sensor because Hondas are very finicky about these parts.

So try cleaning the MAF sensor. If doing so changes nothing, then I would order the correct NTK oxygen sensor and return the Denso one before 30 days have passed since the purchase date.

 

[ToTo17]

So only NTK O2 sensors work lol? not sure everybody uses it and no MAF sensor on Honda's except for 8th gens other civics including mine have an IAT sensor. @HeX and would this work?
https://www.summitracing.com/parts/ngk-24542/overview/year/1998/make/honda/model/civic

 

[HeX]

So only NTK O2 sensors work lol? not sure everybody uses it and no MAF sensor on Honda's except for 8th gens other civics including mine have an IAT sensor. @HeX and would this work?
https://www.summitracing.com/parts/ngk-24542/overview/year/1998/make/honda/model/civic

OK. If there's no MAF sensor then it must be O2 especially considering the third CEL code. If you confirmed through NGKs website that you have the correct part number then that is it.

https://www.ngk.com/product.aspx?zpid=19507

And I'm not saying that no other brand but NTK will function in a Honda but they have a known reputation to malfunction or falter far sooner than later, usually within around 2 years or sooner as you seem to have experienced.

 

[ToTo17]

Well there is now just the P0133 code instead of the other one's. The Denso's I bought specifically for a 1998 Honda Civic EX was about 4 weeks ago and O2 emissions passed with my smog so maybe it is that or maybe it isn't not sure anymore. @HeX

 

[XpL0d3r]

P0133 slow response... check o2 sensor wires for damage or corrosion. OH, and this code can also be caused by an exhaust leak, which you had. You may still have a small exhaust leak -- even something like a tiny hairline crack in the manifold could do it. It can also be caused by the primary sensor being plugged into the secondary bank, and the secondary sensor being plugged into the primary bank.

 

[buzzbombtom]

it is odd that you passed your emission test with a CEL on... you are in california assuming santa rosa is the one by me, do they do an ECU dump or a dyno for a 1998 these days? I know i had a 2005 ford f150 in placer county have just an ECU dump, any pending or faulting codes cause the test to fail. looking to help, not be a jerk, sounds like we are narrowing down your issues with every post!!!