gotchagarage Posted June 12, 2008 Share Posted June 12, 2008 We own for many years a RX300 ( year 2000 ). Last month the check engine light came on, we own a universal garage so I connected a OBDII scan tool and found code 0171 ( bank 1 lean ) My first thought was : probably a bad oxygen sensor, but I connected a Elmscan interface to my laptop and all voltage readings seemed to be correct. I did reset the OBDII code 0171 and test drove again the car with scantool connected, at that moment the overdrive was working, after a mile the check engine light came on and after 10 seconds the overdrive was gone. I did read the OBDII scantool and again the same 0171. I decided to reset this code again, continued my testdriving and yes at that moment the overdrive was working, but after one or two miles check engine light came on and overdrive not working anymore. I have been reading on several forums and know I'm not the only one with overdrive problems. I think the problem is not inside the transmission, we did oil changes / oil filter every 30k miles. Could this problem be related to the knock sensors ? Can anyone give me a logical explanation for this ? Andy / Dutch Caribbean. Quote Link to comment Share on other sites More sharing options...
blk_on_blk Posted June 12, 2008 Share Posted June 12, 2008 From my understanding, when the transmission is told the engine is not performing with enough power, it will disengage the overdrive. This has to do with what code the ECU pops up. I had this happen with a faulty coil pack. As soon as the coil pack went bad, the engine ran rough, the CEL popped on, and my tranny wouldn't shift into overdrive. When I replaced the coil pack and reset the ECU, it took a few miles of driving to get the ECU to learn the current status, but everything went back to normal. So, it sounds like the 0171 code is one of the codes that tells the transmission to not go into overdrive. I'm sure once you remedy the CEL code situation, the transmission will learn all is fine and work properly. By the way, even though the voltage reading looks good on the oxygen sensor, an old sensor can be slow to come up to proper voltage, and that triggers the CEL code. It's not the voltage reading itself that is causing the fault code, but rather it's slow response time. Either way, the O2 sensor is faulty, and I'm confident replacing it should remedy all your problems. Hope this helps. Quote Link to comment Share on other sites More sharing options...
H. Dindi Posted August 12, 2008 Share Posted August 12, 2008 We own for many years a RX300 ( year 2000 ). Last month the check engine light came on, we own a universal garage so I connected a OBDII scan tool and found code 0171 ( bank 1 lean ) My first thought was : probably a bad oxygen sensor, but I connected a Elmscan interface to my laptop and all voltage readings seemed to be correct. I did reset the OBDII code 0171 and test drove again the car with scantool connected, at that moment the overdrive was working, after a mile the check engine light came on and after 10 seconds the overdrive was gone. I did read the OBDII scantool and again the same 0171. I decided to reset this code again, continued my testdriving and yes at that moment the overdrive was working, but after one or two miles check engine light came on and overdrive not working anymore. I have been reading on several forums and know I'm not the only one with overdrive problems. I think the problem is not inside the transmission, we did oil changes / oil filter every 30k miles. Could this problem be related to the knock sensors ? Can anyone give me a logical explanation for this ? Andy / Dutch Caribbean. Were you able to solve your CEL 0171 code? If so could you tell us what have you done? I also have a 2000 Lexus RX300 at 80K miles and having problems with the same 0171 code... I cleared it several times and within 5-10 miles of driving it comes back... It causes the car to switch into the safe (fuel rich) mode which is causing power loss (slow acceleration), some (burnt!) fuel smell when the car is parked in the garage after a drive. I have cleaned the MAF once with an electronics spray cleaner which did not solve the code 0171 problem... I had also replaced the A/F ratio sensor (Bank 1 sensor 1) with an original Denso sensor about a year ago which had then solved a different CEL code... I would like to learn from your experience if you don't mind sharing... Quote Link to comment Share on other sites More sharing options...
hmikos Posted August 14, 2008 Share Posted August 14, 2008 Were you able to solve your CEL 0171 code? If so could you tell us what have you done?I also have a 2000 Lexus RX300 at 80K miles and having problems with the same 0171 code... I cleared it several times and within 5-10 miles of driving it comes back... It causes the car to switch into the safe (fuel rich) mode which is causing power loss (slow acceleration), some (burnt!) fuel smell when the car is parked in the garage after a drive. I have cleaned the MAF once with an electronics spray cleaner which did not solve the code 0171 problem... I had also replaced the A/F ratio sensor (Bank 1 sensor 1) with an original Denso sensor about a year ago which had then solved a different CEL code... I would like to learn from your experience if you don't mind sharing... I can't speak for the original poster. This has been my experience. Have a '99 with 125k miles that continues to generate P0171 codes. Cleaned the MAF - no change. Replaced the A/F Sensor - Ran better, but continues to give the P0171. My OD is working despite the P0171. When I go wide open throttle or close to WOT, the engine completely chokes up. Loses power, barely accelerates. Until I cross that threshold, the engine seems strong. My father, who is a retired Ford mechanic, is convinced it is a vacuum leak. I have not had any luck finding the vacuum leak yet. I'm going to take a look for that hose on the back of the air box next. After that I'll look for the vacuum leak a few more times before I start replacing more parts. Quote Link to comment Share on other sites More sharing options...
handjrs Posted October 19, 2008 Share Posted October 19, 2008 Were you able to solve your CEL 0171 code? If so could you tell us what have you done?I also have a 2000 Lexus RX300 at 80K miles and having problems with the same 0171 code... I cleared it several times and within 5-10 miles of driving it comes back... It causes the car to switch into the safe (fuel rich) mode which is causing power loss (slow acceleration), some (burnt!) fuel smell when the car is parked in the garage after a drive. I have cleaned the MAF once with an electronics spray cleaner which did not solve the code 0171 problem... I had also replaced the A/F ratio sensor (Bank 1 sensor 1) with an original Denso sensor about a year ago which had then solved a different CEL code... I would like to learn from your experience if you don't mind sharing... I can't speak for the original poster. This has been my experience. Have a '99 with 125k miles that continues to generate P0171 codes. Cleaned the MAF - no change. Replaced the A/F Sensor - Ran better, but continues to give the P0171. My OD is working despite the P0171. When I go wide open throttle or close to WOT, the engine completely chokes up. Loses power, barely accelerates. Until I cross that threshold, the engine seems strong. My father, who is a retired Ford mechanic, is convinced it is a vacuum leak. I have not had any luck finding the vacuum leak yet. I'm going to take a look for that hose on the back of the air box next. After that I'll look for the vacuum leak a few more times before I start replacing more parts. Ours did that and it was caused by faulty knock sensors. If the system detects conditions that may damage the engine, it will limit the amount of load that it will allow it to be put under Quote Link to comment Share on other sites More sharing options...
Ericok Posted October 20, 2008 Share Posted October 20, 2008 Every time I've had P0171, cleaning the MAF fixed it. You have to clean the inside MAF wires AND the outside temperature sensor using CRC aerosol throtle body cleaner. It comes in a spray can - just blast the inside and outside until they are shiny clean. Using alcohol (which some recommend) doesn't work. If cleaning doesn't do it for you, you have to replace the MAF. Quote Link to comment Share on other sites More sharing options...
H_N Posted April 28, 2022 Share Posted April 28, 2022 I had similar problem with VSC and CEL indicators and overdrive. When I checked the MAF sensor I saw that one side of the glass tip on the sensor was very dirty. I dipped that sensor glass tip in cleaning alcohol and then cleaned it with a fine brush to remove all the dirty stuffs. The air filter was also dirty so I replaced with a new air filter. Happy to report that the problem associated with VSC and CEL indicators and overdrive was gone. Quote Link to comment Share on other sites More sharing options...
H_N Posted April 28, 2022 Share Posted April 28, 2022 I had similar problem with VSC and CEL indicators and overdrive. When I checked the MAF sensor I saw that one side of the glass tip on the sensor was very dirty. I dipped that sensor glass tip in cleaning alcohol and then cleaned it with a fine brush to remove all the dirty stuffs. The air filter was also dirty so I replaced with a new air filter. Happy to report that the problem associated with VSC and CEL indicators and overdrive was gone. Forgot to mention that mine is 2002 RX300 all wheel drive. Quote Link to comment Share on other sites More sharing options...
Craiggnogg Posted November 13, 2023 Share Posted November 13, 2023 Not sure if thread is still alive again 2000 rx 300 not shifting into overdrive no engine codes or lights are popping. I just cleaned my Maf still no 4th gear and no codes… my girl was driving the car and when I checked oil and violent were damn near tapped out filled cooper and did an oil change while I was cleaning maf so nothing changed did a hard reset and pulled the battery for 30 mins to see if it would give me some love but still no 4th gear/overdrive my next step is the over drive sensor (because it would tube the cheap fix) but if anyone has found something that might be faster and or cheaper to look at people love any info Quote Link to comment Share on other sites More sharing options...
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