CEL P0138 help. - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

Saviorself · 08-06-2018, 10:12 PM

A couple weeks ago I voyaged to Ptuning to finally get my flex fuel kit and tune. Nearly spent all day patiently waiting for Toan to work his magic.
At the end of the day she was ready to go home and felt amazing, but halfway back home to NC I had a P0138 CEL come on. I called them the next day and obcourse had me send them some data logs. Toan revised and confirmed everything was running smooth and correctly compensating for the different types of fuel. He stated,” Your P0138 code is for the secondary O2 sensor. We did not use your O2 sensor plug for the flex fuel input, so the ECU should not be throwing a code for that”. And had me make sure it was plugged in tightly and snug. And so I cleared the code and bang! Came back up. I jut replaced the 02 sensor yesterday and drove 20 minutes to work this morning with no CEL. Turned the car on at the end of the day to warm her up before I head back home and bang! Again the same CEL.
Any advice is greatly appreciated

churchx · 08-06-2018, 11:33 PM

Check wiring of sensor?

guybo · 08-07-2018, 06:20 AM

If the O2 sensor is removed from the bung and left dangling instead of properly stowed away while they are working on it, the sensor can get damaged. Wiring can get damaged too. It has to be tested

Don't replace parts (esp expensive ones) unless you KNOW what the problem is. you guessed and guessed wrong.

steve99 · 08-07-2018, 11:24 AM

If you flex kit is evap connected the rear 02 sensor should be normal. Maybe log the rear 02 sensor volts if you have ecutek cable. It might be wiring fault or short check cable not damaged

Many ecu inputs are pulled high by ecu if open circuit.

also this could be due to running rich as this is high volts on sensor.

https://www.engine-codes.com/p0138_subaru.html

maybe watch here and part 2. unfortunately some tunes may disable ltft so may not work on your tune

[ame]https://www.youtube.com/watch?v=5WnM_NsOtd8[/ame]

check your AFR vs commanded AFR and your long term fuel trims. high trims or afr richer than commanded afr by a large margin may indicate an issue like exhaust leak or a problem with flex fuel system causing car to run rich

08-06-2018, 10:12 PM	#1
Saviorself Member Join Date: Mar 2016 Drives: 13' BRZ Location: Chula Vista CA Posts: 13 Thanks: 0 Thanked 1 Time in 1 Post Mentioned: 1 Post(s) Tagged: 0 Thread(s)	CEL P0138 help. A couple weeks ago I voyaged to Ptuning to finally get my flex fuel kit and tune. Nearly spent all day patiently waiting for Toan to work his magic. At the end of the day she was ready to go home and felt amazing, but halfway back home to NC I had a P0138 CEL come on. I called them the next day and obcourse had me send them some data logs. Toan revised and confirmed everything was running smooth and correctly compensating for the different types of fuel. He stated,” Your P0138 code is for the secondary O2 sensor. We did not use your O2 sensor plug for the flex fuel input, so the ECU should not be throwing a code for that”. And had me make sure it was plugged in tightly and snug. And so I cleared the code and bang! Came back up. I jut replaced the 02 sensor yesterday and drove 20 minutes to work this morning with no CEL. Turned the car on at the end of the day to warm her up before I head back home and bang! Again the same CEL. Any advice is greatly appreciated

08-07-2018, 11:24 AM	#4
steve99 Banned Join Date: Dec 2013 Drives: FT86 Location: Australia Posts: 7,996 Thanks: 1,035 Thanked 4,994 Times in 2,984 Posts Mentioned: 598 Post(s) Tagged: 2 Thread(s)	If you flex kit is evap connected the rear 02 sensor should be normal. Maybe log the rear 02 sensor volts if you have ecutek cable. It might be wiring fault or short check cable not damaged Many ecu inputs are pulled high by ecu if open circuit. also this could be due to running rich as this is high volts on sensor. https://www.engine-codes.com/p0138_subaru.html maybe watch here and part 2. unfortunately some tunes may disable ltft so may not work on your tune [ame]https://www.youtube.com/watch?v=5WnM_NsOtd8[/ame] check your AFR vs commanded AFR and your long term fuel trims. high trims or afr richer than commanded afr by a large margin may indicate an issue like exhaust leak or a problem with flex fuel system causing car to run rich Last edited by steve99; 08-07-2018 at 11:35 AM.

08-06-2018, 11:33 PM	#2
churchx Senior Member Join Date: Mar 2015 Drives: 2014 GT86 Location: Latvia, Riga Posts: 4,335 Thanks: 698 Thanked 2,086 Times in 1,436 Posts Mentioned: 53 Post(s) Tagged: 1 Thread(s)	Check wiring of sensor?

08-07-2018, 06:20 AM	#3
guybo Huge E85 fan! Join Date: May 2016 Drives: 2016 Scion FRS Location: Tampa, FL, USA Posts: 1,850 Thanks: 539 Thanked 1,010 Times in 605 Posts Mentioned: 32 Post(s) Tagged: 0 Thread(s)	If the O2 sensor is removed from the bung and left dangling instead of properly stowed away while they are working on it, the sensor can get damaged. Wiring can get damaged too. It has to be tested Don't replace parts (esp expensive ones) unless you KNOW what the problem is. you guessed and guessed wrong.

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