2002 Toyota Avalon Overheating with Codes P1656, P1135, P1663, and P1155 - Troubleshooting Guide
Hi everyone, I own a 2002 Toyota Avalon and am currently experiencing several trouble codes: P1656, P1135, P1663, and P1155. The vehicle is showing signs of overheating, with the temperature gauge indicating high temperatures on the dashboard—though this doesn't always align with the actual radiator temperature. During acceleration, the temperature gauge rises significantly, but when driving in traffic, it returns to normal. This inconsistent behavior raises concerns about potential engine or cooling system issues. I'm looking for insights from other owners who have encountered similar symptoms or resolved these codes. Any advice on diagnosing or fixing these specific fault codes would be greatly appreciated.
The combination of P1656 and P1663, along with overheating symptoms, may indicate low oil pressure. First, verify the oil pressure using a gauge to confirm this possibility. If confirmed, address the issue before moving on to the VVT (Variable Valve Timing) or OCV (Oil Control Valve) related codes. P1135 and P1155 are typically linked to oxygen sensor or heater circuit faults—these may point to faulty sensors themselves rather than wiring issues. Consider replacing the relevant sensors if diagnostics confirm their failure.