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PO717 Code on 2003 Toyota Sienna: Causes, Diagnosis, and Cost-Saving Tips

Model: 2003 Toyota Sienna Fault Code: P0717 Posted: 2011-01-08 15:03

Hi everyone, I'm new to this forum. I recently replaced the O2 sensor on my 2003 Toyota Sienna with a 3.0L engine. The vehicle initially had rough idling due to a clogged IAC valve, but it started stalling frequently when cold and now throws a PO717 code. After researching, possible causes include bad wiring connections, short circuits, or a faulty transmission revolution sensor. I plan to check the electrical connections with a small amount of grease, but I'm unsure if this diagnosis is accurate. Before spending $125 on an electronic sensor that I don't know how to test properly, I'd appreciate expert opinions. Thanks in advance for your insights.

Related fault codes
P0717
Comments (8)
Anonymous 2011-01-08 15:26

Without a dedicated OBD-II scanner, diagnosing PO717 can be challenging and may lead to inaccurate conclusions.

Anonymous 2011-01-08 19:32

What type of scanner do I need? I have access to various tools. I believe the key is retrieving the actual code from the ECU using a proper OBD-II device.

Anonymous 2011-01-08 23:01

A professional-grade OBD-II scanner that can display live sensor readings—like transmission revolution speed—is ideal for accurate diagnosis. Without it, troubleshooting relies heavily on a digital multimeter (DVOM) and circuit diagrams.

Anonymous 2011-01-09 07:00

I'll connect a more advanced scanner tomorrow. If the system indicates a faulty transmission revolution sensor, does anyone know how to test it? For example, what resistance values or continuity checks are expected?

Anonymous 2011-01-09 12:23

Test for open circuits or high resistance between the sensor and module using standard electrical testing methods. If all tests pass, then replacing the sensor becomes a last resort—there’s little else to consider without some risk.

Anonymous 2011-01-10 02:36

If the scanner shows a transmission revolution sensor fault, do you know how to test it? Specifically, what resistance values or continuity should I expect?

Anonymous 2011-01-10 06:07

I'm not suggesting you don't know circuit testing—just that sensors like this generate variable voltages (like ABS sensors), so an ohm reading isn’t always reliable. Use a DVOM to check for continuity and voltage output, but if you're unfamiliar with how to interpret schematics or sensor behavior, purchasing a new part might be the safest option.

Anonymous 2011-01-15 16:51

I cleaned both the throttle body and IAC valve. Afterward, the idle stabilized significantly, and the check engine light turned off. A transmission technician confirmed that PO717 is triggered when idling is unstable—so once the CEL is off, further testing may not be necessary. Thanks for your help!