CEL P0121 and P0221 (OFT tune + EL Catless Header)
 

Recently swap back to stock exhaust. My BRZ has OFT and EL Catless header. No CEL before swap back to stock exhaust. However, I don't feel any problem or hesitation of acceleration while driving. I am going to delete the error code using OFT and see if the codes comes back.

Do you guys have similar situation before? Many Thanks.


I search CEL codes. It is related to Throttle Position Sensor.
Throttle Pedal Position Sensor/Switch (TPS) A Circuit Range Performance Problem


According to some general error code guideline.
Symptoms of a P0121 trouble code could include:

• Malfunction Indicator Lamp (MIL) illumination (Check Engine Light or Service Engine Soon light)
• Intermittent stumble on acceleration or deceleration
• Blows black smoke on acceleration
• No start

Common Problems That Trigger the P0221 Code

• Defective Throttle/Pedal Position Sensor or Switch
• Dirty or carbon-filled Throttle Bore
• Torn or jammed floor mats
• Faulty or corroded Throttle/Pedal Position Sensor/Switch wiring or connections

Hopefully someone can chime in real soon!

https://www.autocodes.com/p0221.html


http://www.autocodes.com/p0121_subaru.html

Both codes relate to the throttle position sensor, check plugs at throttle body.

You somtimes get random codes after a ecu flash. If it occurred directly after flash that likely the case.

extremly unlikely it tune related

when you start car directly after reflash let it idle for at least a minute and dont touch throttle during that period, ecu is calibrating all sorts of things during that period.




Clear the codes if they dont return , happy days, if they do they you likly have a problem with the throttle sensors or wiring connectots or throttle body.

Thanks Steve. I will see if it is coming back. Happy New Year.

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i think i remember somone with similar codes, he had some crud stuck in the throttle plate stopping it closing\opening fully , bit if air filter or something, think a mouse or rat chewed through air filter getting at seeds stuck in filter. weird stuff happens

check the throttle plate in throttle body if it comes back

Checking throttle body and plate is great idea.

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Want to update this issue. The CEL P0121 was happened on 12/27/2016. Yesterday, it happened again. So, it is 2 months and about after I deleted the CEL using OFT. In this two months, I drove at least 2500 miles. Currently, the car only have about 6800 miles.


With or without the CEL on, the car still feel strong. I can still accelerate to redline without any issue.


So, I delete the code again and see how long it comes back. I didn't have chance to open up the throttle body since it didn't comes back for so long.


Subaru has 5 years warranty related to engine issue. So, may be I just wait until it show more often and bring it back to fix it. (it is a hassle since my BRZ has after market header and light weight pulley)


Anyway, I will keep you guys post.

So you have a tune, header and pulley but this is a warranty problem?

I think that Dealer usually blame on your mod when they have engine issue. With OFT and header, I am sure they will void my warranty if I am taking it back to dealer. I guess, if my car have more obvious issues like unstable idle speed, black smog and acceleration problem, I probably will put all engine relate mod back to OEM and bring it to dealer for CEL.

Want to update about the issue. According to Shiv of OFT, it should be related to Throttle Pedal Position Sensor and not related to OFT mod. I made a decision to buy a replacement of the Pedal Position Sensor - part number 36010CA070. Although, my car is still under warranty, I wouldn't want to bring the car back to dealer for many reasons. I found used one on Ebay selling it at around $40.


It cost about $110 new.
http://parts.subaru.com/p/Subaru__BR...6010CA070.html


It was a very easy installation. 2 screws and unplug a connection.


Test drive the car after installation, it seems the car accelerate a bit more smooth. Let's see how it go after few thousand miles.