Codes P0135 and P0505?

AMIR PARSA

MEMBER
2004 TOYOTA CAMRY
2.4L
4 CYL
2WD
AUTOMATIC
300,000 MILES

Hi mate,

The car listed above 2AZFE, when start in the morning, the car has a hard time starting. When I crank the engine, it struggles to stay on unless I press the gas pedal. After giving it some gas and letting it run for a while, it stabilizes and runs fine. The check engine light is on, and we scanned the ECU with a diagnostic tool and retrieved some error codes p0135 and p0505. We already replaced the oxygen sensor, but the issue wasn't resolved. We also cleaned the idle air control valve, the one that controls the airflow when the throttle is closed during cold starts, but that didn’t fix it either. Now I’m trying to figure out what could be causing the problem, and if there are specific wirings I should check. Can you help me diagnose this?

Friday, April 25th, 2025 AT 5:59 PM

1 Reply

KEN L

MASTER CERTIFIED MECHANIC
51,685 POSTS

When you replace the oxygen sensor you replace the primary sensor correct? Also, did you check the air/fuel sensor which can be the same sensor trouble code. In other words, there are two primary sensors, please check the image below.

Code P0135 - O2 Sensor Heater Circuit Malfunction (Bank 1, Sensor 1)

Code P0505 - Idle Air Control (IAC) System Malfunction

There is no idle air control valve on this car, so I am not sure why this p0505 code is there. Perhaps the throttle body is bad, I would replace the additional sensor and the throttle body. Check out the images (below). Let us know how it goes.

Images (Click to make bigger)