Air Intake CEL Fix (P2C9000)

It is generally understood that most aftermarket intakes on the GR Corolla cause a P2C9000 Check Engine Light (CEL). There are a number of mechanical fixes that seem to mostly work but up until now nothing has fully solved the CEL short of an ECUtek tune that would override the check.

 

Fortunately, Toyota has recently released an ECU update via Technical Service Bulletin (TSB) that will widen the PCV pressure threshold to a point where aftermarket intakes no longer trigger this code.

 

The challenge here, is that to get the TSB update on your car you need to show up to a dealership with an active P2C9000 CEL. In order to have an active code, you may need the intake installed that causes the CEL. It is then at the dealership's discretion whether they want to perform a TSB caused by an aftermarket part (they may just turn you away). 

 

Due to this catch-22, 555 Engineering has put together a guide to update your ECU without going to the dealership.

 

Update your own ECU - P2C9000 TSB

Note: At the time of this article, this fix is only available for MY23-24

 

Required Hardware / Software

OBD2 Cable (J2534)

Toyota recommends using a Mongoose Cable which is officially supported by Techstream / GTS+. 555 Engineering uses a Tactrix Open Flash Cable, they are a US based company and this is the cheapest cable we feel comfortable flashing ECUs with. You can try to use the cheap Amazon $35 cables, but you are doing so at your own risk of an ECU brick. Driver support also may be unstable with cheaper cables. Both Mongoose and Tactrix Cables will require drivers to be installed before GTS+ will identify them in the VIM dropdown menu.

 

(Choose one of these)

•  Mongoose Cable
  • https://www.amazon.com/Mongoose-Plus-J2534-Vehicle-Interface-Cable/dp/B097NFNZBG?th=1

•  Tactrix Cable
  • https://www.tactrix.com/index.php?option=com_virtuemart&page=shop.product_details&product_id=17&vmcchk=1&Itemid=53&redirected=1&Itemid=53

• • No Reflash Adapters required for GR Corolla

 

GTS+ (Toyota Techstream) Professional Diagnostic Subscription

• You will need the Professional Diagnostic Subscription which at the time of this article is $70 / 2 days. This is the lowest level of subscription that will give access to ECU flashing. 
  • https://techinfo.snapon.com/tis/register.aspx

 

Recommended

Battery Tender

• ECUs and digital electronics get sad when voltage drops below 12V. It is recommended to have your battery on a tender to maintain minimum voltage (12V) through the flash process. The calibration update will take about 20-30 minutes. 
  • Toyota has a special battery tool that is listed in the TSB, but any decent battery tender will do.
    • Amazon Example: https://shorturl.at/eIFAf
  • If you do not use a tender, we recommend having a minimum 12.6V battery when beginning the update and turning off all accessory power.
    • Unplug the headlights in the engine bay. Once the ECU goes into flash mode it loses sync with the chassis module and the headlights will default to on and accelerate battery voltage drain. 

 

WARNING: Losing power during an ECU flash could result in a bricked ECU. We are not liable for this.

 

Relevant TSBs

T-SB-0021-25 (How to use GTS+ for ECU Calibration)

T-SB-0063-24 (P2C9000 CEL Fix)

 

Instructions:

1. Connect J2534 Cable to OBD2 port (underneath steering column, LH side)
2. Run GTS+
3. Run Vehicle Healthcheck (Follow T-SB-0021-25)
4. Identify current ECU Calibration ID
   
5. Check T-SB-0063-24 and confirm your ECU Calibration ID applies
6. Download applicable updated ECU Calibration by clicking PDF blue hyperlink in "NEW" column shown above in Step 5 image.
7. Open updated ECU Calibration that was downloaded in above Step 6.
8. This will open GTS+ and prompt you thru the Calibration Update. Follow the instructions.
9. Calibration will take around 20 minutes.
10. Congrats you are done. Disconnect battery tender if applicable.

Note: After ECU updates, your key FOB and door locks may temporarily lose sync. They should both resync on their own shortly. 

 

You can confirm the update is working by checking for pending CELs, there should be none now. 

 

 

Additional Reading

For further background on the PCV system, SXTH Element Engineering also did a great technical writeup on this issue here: https://sxthelement.com/blogs/sxth-element-blog/gr-corolla-the-p2c90-saga

 

This article is for the GRC community's benefit and reference. We take no responsibility for outcomes from the use of this article.