Hello,

I need some help figuring out an issue. My 96 Lexus ES300 suddenly started have issues staying on and would idle roughly. No check engine light was triggered to give me direction. I tried replacing the Camshaft position sensor but no change happened. I then tried replacing the Crankshaft Position sensors and still no change. Then I changed the throttle body position sensor and still no change. I eventually noticed that the Camshaft position sensor connector was damaged and replaced it. My car seemed to be back to normal so I though it was fixed. After drivjng it about 15-20 miles the check engine light came on and I scanned code P0121 (Throttle / Pedal Position Sensor / Switch 'A' Circuit Range / Performance). This was the first time I received this code. I cleared the code, unplugged the battery for over 30 minutes, but the code kept returning after short test drives. I put back in the original throttle position sensor, cleared the code, unplugged the battery for several hours, but the code still came back on after short test drives. The TPS seems to be working fine so I am very confused. The TPS is testing approximately 16 degrees at idle and approximately 80 degrees WOT. I also check it with a multimeter and did not detect any dead spots. I wonder what is triggering the check engine light now that I know that the Camshaft position sensor connector was the original problem and I put back in the working oem tps sensor? I appreciate any advice you can give. The car is still running strong so I want to get more use out of it if possible. Thanks in advance.

 

Since you found one bad connector/wire what about the one going to the TPS? I don't know the exact numbers but the throttle position never reads 0 or 100%, why Toyota. Have you tried cleaning the throttle body?

 

Hello,

It is pretty normal for the TPS to not reach full 100%, at least as far as I am aware.

P0121 is a bit of a strange one, as it is only triggered if the car is going above 30km/h and the sensor snaps beyond operating limits even once. Something like that usually indicates a Wiring Issue, especially now that you replaced the sensor itself. Inspect the connector that goes to the sensor, often times the isolation wears out right at the rubber seals, causing an intermittent loss of contact.

Hope this helps and best of luck!

 

Thank you. I actually ordered a new TPS sensor connector and it just arrived. I plan to change it tomorrow and will try cleaning the throttle with Seafoam as well. I'll post back after to let you know how that goes.

 

Thank you! I figured the connector could have damaged when I removed it since it is so old. I plan to change the connector this weekend and hopefully the trouble code will stay off. Thanks again

 

Thanks again. I think it was the TPS connector. I went ahead and put in the new connector shortly after I replied to you both and drove my car on the freeway for 40 minutes or so and the check engine light stayed off. Before, it would come back on within 10-20 minutes. I didn't even have to clean the throttle body (but still plan to soon).

 

Cool hope that's a permanent fix. I had a TPS fail recently on me (not my Lexus) the car ran very poorly not much power.