P0137 and P0457 cleared then P0171 and P1153

[Maxdriver3]

Hi guys !


I got a 2007 Impreza for a cheap price, engine and transmission feels very good BUT it had a check engine light on.


I cleard with an OBD2 scanner and an app.
and the car drove fine for about 45 miles, excellent gas mileage and all good.


But ant the end of the day, just when stop at home, the check engine came back.


The codes where

P137 and P0457





I cleared it and drove fine but for 20 miles, then the CEL came back, but with the following codes




The car has removed the original airbox filter REMOVED and instead has a .... , I don know the name of those K&N filter that people use to "tune" cars


Fuel filler cap is good (it makes air coming sound when loosening)





Here are some number when driving WHEN THE CEL WAS OFF.










And HERE are the numbers AFTER the CEL came on.




Notice how the fuel mixture ratio is out of the parameter


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[Charlie-III]

If showing STFT's, sorta ignore them.
If showing LTFT's, what is the number and is it a "+" or "-"?

[Maxdriver3]

An update.
The connector for the canisters purge valve (the one in the i take manifold)
Has 12v signal, but no curren, so it does not open the valve, i connected a small lamp and it does not light the lamp, but the multimeter reads 12v.

What is this?

[Elbert Bass]

Originally Posted by Maxdriver3

An update.
The connector for the canisters purge valve (the one in the i take manifold)
Has 12v signal, but no curren, so it does not open the valve, i connected a small lamp and it does not light the lamp, but the multimeter reads 12v.

What is this?

You are measuring power supply to the solenoid. The ECM provides a duty cycle ground to activate. The purge solenoid is only activated under certain conditions while driving. You can force the purge to cycle - look under the driver side dash or behind the carpet on driver floorboard left or right for two 2 terminal GREEN plugs. Those are the Test Mode connectors. Plug them together and turn on the key - that will cycle the fan relays, purge solenoid, vent solenoid and several other items.

You mention several codes but not sure what you have now.

P0137 is usually a fault in the sensor or wiring for the rear O2 sensor (B1S2)

P0457 is usually a faulty gas cap - regardless of swooshing sound when opened (the test parameter for that code is pulling a vacuum, not pressurizing). If the code returns after tightening the cap and clearing the code then the next step is replace the gas cap with OEM cap.

P0171 Can be a vacuum leak (anywhere after MAF), a crack or leak in the exhaust manifold, a faulty A/F sensor. (B1S1)

P1153 can be bad wiring/poor connection or faulty A/F sensor (B1S1)

[Maxdriver3]

Hey, thank you a lot for your reply.
Currently i am only getting consistently th P0457 code.

About the purge solenoid valve (the one under the hood and behind the alternator) I thought that valve would open immediately after the engine warms up.

[Elbert Bass]

Originally Posted by Maxdriver3

Hey, thank you a lot for your reply.
Currently i am only getting consistently th P0457 code.

About the purge solenoid valve (the one under the hood and behind the alternator) I thought that valve would open immediately after the engine warms up.

Nope. Canister purge introduces excess gas vapor to the intake. The amount depends on how much vapor is stored in the canister. At idle that could cause too much enrichment and at WOT the ECM is in open loop (running a preprogramed fuel deliver) so you don't want the enrichment at those times. Purge also operates off a duty cycle (not full open/not full closed). This happens mostly at cruising speeds so it can better monitor and control the fuel mixture.

As far as P0457 as I said first tighten the cap - clear code. If the code returns replace the cap with a Subaru gas cap - NO AFTERMARKET CAP.
If the code return then you need to inspect for loose/chewed/broken hoses or rusted tank, holes, faulty vent and pressure control solenoids.
Fortunately that code is a major leak and is usually obvious - hence the gas cap replacement being the default first option. Also it is very common for those caps to fail the test.

So you understand how the test works: as the car is driven and if: 1 the outside temperature is above 50 degrees, and 2 the tank has a set amount of fuel, 3 the car is driven at a steady speed, the drain valve on the canister is closed. The purge valve is opened and that allows engine vacuum to act on the fuel tank, creating low pressure in the tank. The ECM watches that fuel tank pressure and if the pressure does not drop or maintain within a known time/value it sets a code. It can also determine the size of the leak so it will give you different codes for differing size leaks.

[Maxdriver3]

Ok, that information was PRETTY HELPFUL.
I replace the fuel cap , put an original one on it.

I got a smoke machine.
In case the code comes back.

Where i shouldnconnect the smoke outlet of the machine? In the gas filling neck itself?

[Elbert Bass]

Originally Posted by Maxdriver3

Ok, that information was PRETTY HELPFUL.
I replace the fuel cap , put an original one on it.

I got a smoke machine.
In case the code comes back.

Where i shouldnconnect the smoke outlet of the machine? In the gas filling neck itself?

I usually connect to the purge hose on the solenoid up front, that way you are testing the whole system. Don't forget to pull the drain hose on the canister (big hose) and cap the fitting on the cannister to seal the system.
If your smoke machine has a guage that can tell you how big the leak is - RTFM.
Get a really bright light or flashlight, that helps locating smoke source.

[Maxdriver3]

I got the Icon one that has harbourfreight, it comes with a yellow flashlight and the machine itself measures the leak size.

I gave the car to my mother so she uses while I work in her, so far 3 days without the light

[Maxdriver3]

Morning!
Check engine had 4 days without coming back, then yesterday came back, BUT due the catalitic.

Is there a posibility that were due the O2 Sensor?

I remember i had a 2007 Outback that gave symptons like a misfire and hesitation when hard acceleratiing, i got a message that the catalitic was the culprit, but i decide to change the o2 sensors and the problem went away

[Elbert Bass]

Originally Posted by Maxdriver3

Morning!
Check engine had 4 days without coming back, then yesterday came back, BUT due the catalitic.

Is there a posibility that were due the O2 Sensor?

I remember i had a 2007 Outback that gave symptons like a misfire and hesitation when hard acceleratiing, i got a message that the catalitic was the culprit, but i decide to change the o2 sensors and the problem went away

Depends - which code for converter? P0420?

P0420 is an efficiency code. A proper diagnosis involves getting the car warmed up, drive a steady speed above 40 MPH on level ground a few miles. Record with a graphing scanner the A/F (B1S1) signal and the O2 sensor (B1S2). The A/F signal will move back and forth across lean/rich. The O2 sensor should maintain a relatively steady value. If the O2 sensor value mirrors the A/F signal or oscilates greatly then the catalyst is bad. If the A/F signal is jumpy and erratic that could mean a faulty A/F sensor - as long as it is not reading an actual faulty mixture due to misfires or lousy injectors.

If the cat is bad then you need to find out why - is it burning oil - misfiring - too rich a mixture - cheap fuel - too much alchohol in fuel - even the A/F sensor or a cheap aftermarket replacement catalyst.

During that drive cycle test you can let off the throttle and watch the sensors. The A/F should transition lean quickly before the O2 sensor transitions lean. If the A/F is slow or doesn't show a full swing to lean then the A/F sensor could be the culprit.
Subaru has a whole workbook dedicated to diagnosing P0420 and catalyst problems if you can find a copy.

[Charlie-III]

I have also seen P0420 (on various brands) when there is an exhaust leak within a foot or so of the downstream O2 sensor. Yes, makes no sense, I expected exhaust to blow out the hole, but it can still trip the CEL.
Check for exhaust leaks, My test is get the front of the car up. Start it and let idle. Crawl under and have a friend block the tailpipe (rag, heavy gloves, etc.) while you listen/feel for leaks.
Don't get burned.
Fix leaks if you find any.
Drive the caar and see if CEL comes back.

Dumbest one I dealt with was a failed Y-pipe. It was replaced, but the CEL came back. Put the car up, found a 1/8" long spot in a weld not complete in the NEW Y-pipe. That was rewelded and car sent back to customer. No CEL after that.

YMMV

[Maxdriver3]

Morning guys!

I have one doubt
Investigating old records found that previous three Outback I have worked with have had evap related codes

The first one was an o2 sensor
The second one, an 02 sensor too
The third one was an extremely dirty air filter, in fact I got the car an a cheaper price because the owner didn't solved the car had check engine light on, and after i replace the air filter the check engine gone after couple hour driving.
QAl of those three cars had two to three codes but with evap one always present...

Now with this Impreza, that only shows the P0457 and no other...
Should i try luck changing the o2 sensor

[Elbert Bass]

Originally Posted by Maxdriver3

Morning guys!

I have one doubt
Investigating old records found that previous three Outback I have worked with have had evap related codes

The first one was an o2 sensor
The second one, an 02 sensor too
The third one was an extremely dirty air filter, in fact I got the car an a cheaper price because the owner didn't solved the car had check engine light on, and after i replace the air filter the check engine gone after couple hour driving.
QAl of those three cars had two to three codes but with evap one always present...

Now with this Impreza, that only shows the P0457 and no other...
Should i try luck changing the o2 sensor

Have you performed your smoke test?

If you can fix an evap code with an O2 sensor then you are a much better technician than I am.

[Maxdriver3]

Originally Posted by Elbert Bass

Have you performed your smoke test?

If you can fix an evap code with an O2 sensor then you are a much better technician than I am.

Smoke test yest, only a pretty small leak at the canister.


I have record of three subaru i have had that UNTILL NOW that i opened the record i keep for each car is when i realized they all had evap codes on.


Two of them i just replaced the downpipe o2 sensor and all the codes were gone, and the third one, an 2014 outback my mother still have, within the codes it had was the evap (it is now when irealize that, back them i just sow a bucnh of codes), in that last one i just discovered a clogged air filter, replace, and all codes gone.


Here a capture of a scan i did almost two years ago for that car.








Previous two (2005 H6 outback and 2007 Outback) also had evap codes but i didnt focus on that because i had no idea what evap was then, i just replace the o2 sensor.


Here a capture of 5 yeas ago of the 2007 outback codes before replacing the o2 sensor

[Elbert Bass]

Originally Posted by Maxdriver3

Smoke test yest, only a pretty small leak at the canister.


I have record of three subaru i have had that UNTILL NOW that i opened the record i keep for each car is when i realized they all had evap codes on.


Two of them i just replaced the downpipe o2 sensor and all the codes were gone, and the third one, an 2014 outback my mother still have, within the codes it had was the evap (it is now when irealize that, back them i just sow a bucnh of codes), in that last one i just discovered a clogged air filter, replace, and all codes gone.


Here a capture of a scan i did almost two years ago for that car.








Previous two (2005 H6 outback and 2007 Outback) also had evap codes but i didnt focus on that because i had no idea what evap was then, i just replace the o2 sensor.


Here a capture of 5 yeas ago of the 2007 outback codes before replacing the o2 sensor

Your captures are not showing up. I would be real interested in what the exact evap codes those vehicles had that were resolved by replacing an O2 sensor.

[Maxdriver3]

Sorry for that, will confirm you shortly

[Charlie-III]

Figures, I help on forums with P0420 or P0430, now a family car popped the P0430.
Sigh.

[Elbert Bass]

Originally Posted by Charlie-III

Figures, I help on forums with P0420 or P0430, now a family car popped the P0430.
Sigh.

You just waited too long to perform some sort of preveventative maintenance...

[Charlie-III]

Originally Posted by Elbert Bass

You just waited too long to perform some sort of preveventative maintenance...

Parents Lincoln MKX.
Now that I think of it, I was asked to reset oil change interval without an actual oil change.
Karma getting back at me.....

It's just overdue, not like double.
Still, starting checks in the am.