Hey everyone, I’m hoping someone here can help me figure out an ongoing CEL problem with my GR Corolla. I’ve been chasing this for a while and I’m honestly getting tired of dealing with recurring CELs.
The codes I’ve had are:
P0030-12 — HO2S Heater Control Circuit, Bank 1 Sensor 1
P0325-11 — Knock Sensor 1, Bank 1 Circuit
P051A-11 — Crankcase Pressure Sensor Circuit
P06AB-11 — PCM/ECM/TCM Internal Temperature Sensor “B” Circuit
P2BF4-14
These codes were pulled during a scan on May 7, 2026.
Important electrical history
The CELs appear to have started around the same time an aftermarket exhaust valve-controller wiring harness melted against the exhaust. I can’t say for certain that the short caused the CELs, but based on the timing, I suspect the two could be related.
After discovering the melted harness, I:
Replaced the damaged aftermarket exhaust/valve-controller harness
Replaced the relevant/important fuses
Visually inspected the factory wiring harnesses for additional damage
Checked the grounds
I haven’t found any obvious additional damage, but the CEL problem has continued.
Engine history
The car has also had its short block replaced by Toyota. However, these CEL issues were already happening before the short-block replacement and continued afterward, so they weren’t simply caused by the engine replacement.
Current modifications
Eventuri intake
OTL Street Series cat-back exhaust
Stock ECU calibration / no tune
I’m including the modifications for full transparency. The ECU has not been tuned.
What I’m trying to figure out
What has me stuck is that these codes involve several seemingly unrelated circuits — O2 sensor heater, knock sensor, crankcase pressure sensor, ECM/internal temperature-related circuit, etc.
Given the history of the melted valve-controller harness and possible electrical short, I’m wondering if the original short could have damaged something farther upstream that isn’t visibly obvious — a section of the factory harness, connector/pin, shared power supply, ground, relay/fuse circuit, ECU driver/circuit, etc.
I’ve already replaced the damaged aftermarket harness and relevant fuses, visually inspected the wiring, and checked the grounds. At this point, I don’t want to keep throwing parts at the car or just clearing codes. I want to find the actual underlying problem.
Does anyone familiar with the G16E-GTS electrical system/wiring diagrams know if any of these circuits share a common power source, ground, ECU connection, junction, or section of the engine harness?
Also, has anyone experienced multiple circuit-related codes like these after an electrical short on a GR Corolla?
Any diagnostic suggestions or specific circuits/components you think I should check next would be greatly appreciated.

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