How many trips for ECM to self clear a P0156 after replacing O2 sensor?

[cdq109]

Hello,

 

Does anyone know how many trips the ECM requires before it will self-clear a P0156 error code, after the O2 sensor is replaced?

 

I do not want to reset the ECM, as I don't want to drive the test pattern, for quite literally at least the 10th time in the last few months.

 

I've put like 1,300 miles on the damned thing, mostly just driving the test pattern.

 

Moved from the San Diego are to the San Francisco Bay area, and am now in an "enhanced" testing area.

 

It has been like playing a nightmare version of "whack-a-mole". Fix one code another pops up.

 

So far the following items have been replaced (some only after various vague codes only intermittently came on and multiple relearn trips had to be performed) just to get the OBD-II ready paramaters set such that my MIL light was off, and all the required test patterns had passed without any codes being thrown (oh and like 7 Smog re-tests done, none "gross poluters" and hte last one only failing by 1 part per million for Hydrocarbons for the ASM 25 MPH test, everything else was FINE:

• Distributor (Crank position sensor died after ~180,000 miles. Word to the wise NAPA or OEM ONLY! Richporter NS-60 gave me two BAD parts)
• Driver Side Exhaust Manifold (was cracked)
• Driver Side Catalytic Converter (honeycomb was melted, found after cracks in manifold, replacing various 02 sensors--extra O2 from cracks, and extra fuel from ECM dumping more fuel to compensate for a false lean condition = super heated cats and melted substrate for bank 2 (Doh!!!!)
• Driver Upstream O2
• Passenger Upstream O2
• Passenger Downstream O2
• Knock Sensor
• New Plugs
• New Plug Wires
• Tightened Ground Screws in Speedometer Head Unit (after getting a code for that early on)
• 195 Degree Thermostat Installed
• Ignition Timing Set, tweaked, re-set, re-tweaked etc...
• MAF sensor cleaned (CRC MAF cleaner)

So today I finally did the Seafoam into the break booster vacuum line treatment.

 

After that cleared, took it on a road test.

50 miles later the Driver Side Downs Stream O2 Sensor (the only one I had not replaced yet) threw a code and my MIL check engine light came on.

So anyway I am 1 ppm away from passing the damned smog on this thing (CRC Garunteed to Pass tried way before the crack in exhaust manfold was found, so fuel system should be good).

So tomorrow I dutifully plan on replacing that sensor (I don't doubt that the Seafoam treatment is tied to the code being thrown, but only because the O2 sensor was in need of replacement anyway and had reported borderline passing voltages previously). It's is ANCIENT (bought the truck in like 2001 and I don't think I've had to replace O2 sensors until 2016, so I can't complain there...)

But the thought of me having to reset the ECM for it to learn the fuel/air trims again and go through all the test patterns, well it's enough to make me want to start drinking....HEAVILY...(kidding, mostly...a guy can only take so much...).

The only thing worse than resetting the ECM and having to drive the test pattern again (2x) would be to not reset it, only to learn that the ECM has to go through like 200 full trips before it will self clear the code.

I know the FSM says the "Two Trip Logic" requires that the same code be present during two consecutive trips, but it does not say how many consecutive trips might allow the ECM to clear itself of the code.

I know the normal process is for people to just reset the codes on the ECM via scantool, I just can't bare the thought of doing that again.

 

www.lyberty.com/car/Maxima_A32_docs/NTB98-018c.pdf

 

[pathfinder1990]

I feel foolish saying this after how much thought went into your post however.

 

I have bank 2 02 codes as well..and I simply clear the codes and continue driving. Never done or heard of a test pattern drive (so maybe I'm out of my element) however..I have excellent gas milage and the truck runs like a top...clear codes and go.

[pathfinder1990]

No emmisons testing here. Just looked it up real sorry. That sounds like a true pain. Can you find a "better" mechanic. Someone less anal about 1ppm

Not sure if he has to report and record but at 1ppm you might have passed a second test done back to back..or failed worse.

[cdq109]

Ok, so if you look at page EC-54 of the FSM it states that in asterisk note *2 "MIL will go off after vehicle is drivien 3 times (pattern without any malfunctions.

Also *4 states "The DTC and the freeze frame data will not be displayed any longer after the vehicle is driven 40 times (pattern A) without the same malfunction (The DTC and freeze frame data still remain in ECM)".

[cdq109]

Thanks Pathfinder1990.

Unfortunately in the Great Repulik of Kaliforniastan, the SMOG data gets uploaded directly to the State Smog system at the end of the test (can't even get a printout without the data being reported). So the technician has no say in it, all automated.

Yeah it is killing me because the truck runs GREAT!

Down in San Diego county it was (then) a regular smog area, and it usually passed (maybe with a quick timing adjustment, a new gas cap, plugs or something simple like that) as it was just a two idle speed test.

In the San Francisco Bay area, we are deemed an "enhanced" area, and this requires a dyno simulated acceleration test (putting the engine and whole locomotive system under stress) at 15 mph a 50% engine load and at 25 mph at a 15% Engine load.

The MOST annoying (and criminal) thing is that the state keeps changing the rules (thus the "enhanced") and making the emissions limits MORE STRINGENT THAN WHEN THE VEHICLE WAS MANUFACTURED (i.e. brand new, right off the factory assembly line).

It is a thinly veiled ploy to get old-often paid off vehicles off the roads (But the politicians and Enviro-Geniuses don't give a damn about fiscal stewardship and sure as hell don't care about any individual citizens personal economics).

I'm all for common sense environmental protection, but 50 parts per million for unburnt hydrocarbons?!? Seriously?

With all the warnings they make McDonald's put on their restaurants about cancer causing agents (when you brown potatoes, the acrylamide I believe it is, is made, and is one of the thousands of compounds "known to the State of California (because California knows so much more than everyone else) to be a potential carcinogen....I am surprise they have not declared Environmental War on Bean Burritos and Bean products due to the unnecessary increase release of Methane (unburned hydrocarbons) as a result of eating said food.

Oh sure, they'll pay some folks up to a $1,000 to "Retire" their old (i.e. paid off) car, and they penalize you by making the emissions standards nearly impossible to meet with out replacing parts every two years, that IF they left the cut values where they were, would only need replaced every decade or so, at worse (catalytic converters especially).

It is a total racket.

 

Meanwhile I've driven like 1500 miles now, just driving the test patterns after resetting the ECM.

I refuse to send my truck to the graveyard, it runs great and I've put a lot of blood sweat and tears thus far--I ain't giving up.

BTW I did reset the ECM and just now found the answer to my question in the FSM. I was up looking for that for hours and hours, but the PDF FSM is not test searchable, so just happened to stumble on it tonight.

I'm worried now that I need a valve job or something more substantial (not that I REALLY need a valve job, but rather just to get the stupid emissions with in specs, the new specs, not the old specs.

I'd like to see a Federal Class Action Lawsuit against the California Bureau of Automotive Repair and the California Clean Air Resources Board for making the requirements MORE stringent then they were at date of manufacture of the vehicle. Total and absolute BS in my opinion, and a violation of ownership rights of citizens.

Behavior modification at it's worst. Grrrr....

Edited September 28, 2016 by cdq109

[Remus92]

That sounds horrible! I'm so glad i live in a state without yearly testing!!!!

 

I would just tell you to move. But we all know that isn't ever a viable solution.

[DarekG]

I feel foolish saying this after how much thought went into your post however.

 

I have bank 2 02 codes as well..and I simply clear the codes and continue driving. Never done or heard of a test pattern drive (so maybe I'm out of my element) however..I have excellent gas milage and the truck runs like a top...clear codes and go.

 

I have the same code with no big issues, however lately mileage has been kind of annoying. How far can you go on a tank of premium fuel with regular driving?

 

I can always get a bit further when I drive super, super conservatively but that's not really realistic.

Edited September 28, 2016 by DarekG

[XP382]

On 9/28/2016 at 2:33 PM, DarekG said:

"I can always get a bit further when I drive super, super conservatively but that's not really realistic."

Sorry for reviving an old thread, but just wanted to say that what is crazy about my 96 Pathy is that if I am driving within the city and not going highway speeds, I get about 100 miles a full tank...yeh, it sux.

 

As for driving the highway, and already did 2 1k mile trips that confirm this, basically from the southern end of the Bay Area of Cali to the northern part of the panhandle of Idaho, I got an average of 300 miles per full tank.

 

Doin the math for this, 21 gal tank at 100 miles gives me about 4.76 miles a gal.  And for 300 miles at 21 gal, gives me about 14.29 miles a gal.  Crazy thing is...I looked up on Google what the avg MPG is for the 96 Pathy...I think something is wrong with my truck lol.

 

Used 1996 Nissan Pathfinder - Specs & Features

Fuel & MPG
EPA city/highway MPG	15/19 MPG
EPA combined MPG	16 MPG
Range in miles (city/hwy)	316.5/400.9 mi.
Fuel tank capacity	21.1 gal

Edited March 18 by XP382
Misspelling

[CALPATHY]

Yeah, something is wrong.  My '97 (manual) gets 14-15 in the city and used to get 18-19 on highway, but after installing free-wheeling hubs I get around 20 in unlocked mode. (21 on great occasion with the wind behind me).

[Precise1]

On 3/17/2024 at 6:16 PM, XP382 said:

Sorry for reviving an old thread, but just wanted to say that what is crazy about my 96 Pathy is that if I am driving within the city and not going highway speeds, I get about 100 miles a full tank...yeh, it sux.

 

As for driving the highway, and already did 2 1k mile trips that confirm this, basically from the southern end of the Bay Area of Cali to the northern part of the panhandle of Idaho, I got an average of 300 miles per full tank.

 

Doin the math for this, 21 gal tank at 100 miles gives me about 4.76 miles a gal.  And for 300 miles at 21 gal, gives me about 14.29 miles a gal.  Crazy thing is...I looked up on Google what the avg MPG is for the 96 Pathy...I think something is wrong with my truck lol.

 

Used 1996 Nissan Pathfinder - Specs & Features

Fuel & MPG
EPA city/highway MPG	15/19 MPG
EPA combined MPG	16 MPG
Range in miles (city/hwy)	316.5/400.9 mi.
Fuel tank capacity	21.1 gal

 

So do I!

 

If you don't have an OBD2, go to an autoparts store and have them scan you car for fault codes... I'm wondering if your CEL isn't burned out.

You can always buy one of these transmitter and download InCarDoc or somesuch app for your phone so you always have some onboard diagnostics.

 

With that that bad mileage you should be blowing black smoke or leaving a trail of gas around town.

Any info on vehicle mods such as rims/tires and such?

 

B