rcal

My '01 RX300 failed emissions and before putting in a new cat, we had the code reset and I have to complete a drive cycle to see if the check engine lights come back on. Can someone please tell me where I can get directions for the drive cycle? Thanks

salimshah

The OBDII (which generates CEL) is based on acquiring data from various sensors and the information is processed over time. Depending on what it is ... like misfire (which will show up fairly quickly), ... low evap leak (which needs to be monitored over days) ... produce either an active pending code or Error code or reported as 'channel not ready'. Some I hear are dependent on number of engine start and stop.

Typically the acquisition of data gets done in couple of days of driving. The litmus test is connecting a OBDII reader and does not pop up 'channel not ready'.

You typically have 15 days to have the repairs done and that certificate is like a get out of jail free, if you are stopped for expired inspection sticker.

Salim

Lexmex

Salim hit in the head.

I have seen a lot of information out there and from my own experience I've had different experiences when looking at the drive cycles. For sure, it's good to have and OBD2 scanner that can read the readiness monitors.

Generally, I see it between 15-30 minutes of a single drive, mixing 50 city/50 highway and making sure you get above 55 mph. Sometimes, I have seen it take at least 3 such drives before I see the readiness monitors show OK, particularly the cat and the O2 sensors and when I changed out my cat the previous 2 times, it took about a 10 mile drive back to my apartment (when I was in Mexico) and then a 10 mile drive that night to the track before I saw all readiness monitors set. I basically hit about 15 minutes of city streets, then about 15 minutes of highway, and then another 15 minutes of street to get back to the apartment and roughly the same going to the track, so that total was about 90 minutes over 2 drives. However, when I got back to the apartment only the O2 sensors and cat weren't reset, but that night at the track all was clear and this happened on both times I changed out the cat.

The CEL might not come back on, but the readiness monitors take longer to go to OK.

rcal

thanks guys. I'll try all kinds of speeds and starts/stops throughout the week and i'll check it on the weekend.

carguy07

For what it's worth, mine reset in about 10 minutes of mixed driving, no real highway speeds.

Dhaka

I had changed my O2 sensor for my 2001 RX 300 and drove about 30 miles to my emissions test which I failed, saying the car being "unready." After driving another 20 miles, two days later,I went back for a retest and failed again. I drove about another 60 miles, over half on the Interstate. Again, I went back for a check. Once again, the car showed two counts of being unready. I am at a loss, but in the meantime the car drives like a new car and in the last two days, I have driven over 100 miles. How long should I wait to go back for a recheck? What else should I do? Please help me.

carguy07

Did you reset the computer or just install the new sensor and drive?

kalali

Just to make sure I understand, are we saying that even when the OBDII code reader reads no code found, the car may still fail inspection? Does this apply to only to cats and O2 sensors or it applies to other faults like misfire, etc? I've never experienced this mon readiness condition after resetting for various faults.

salimshah

I dont want to get into semantics of the statement .. but essentially you get "not ready" with the CEL bulb off right after resetting. Here in central Texas one needs road worthy inspection, and you can not reset the CEL and walk in for inspection claiming there is no CEL. You will be promptly told ... come back after few days of driving.

Salim

ATLs460

I do state inspections, and I've seen vehicles take as long as 150 miles before all monitors were ready.

kalali

Thanks. I'm not talking about semantics just trying to understand the condition. So the bottom line is that you reset the code, OBDII scanner reads "No Codes Found" and you drive into the state inspection station and the inspection fails. If that's the case, then obviously "their" scanners are reading different conditions which can not be detected by the off-the-shelf scanners.
I'm asking because I have an occasional single cyl misfire on my Jeep and I'll need to get it inspected in a few months. Wife's RX has been running quite well with no issues.

carguy07

Yes, you can show no codes and still fail if the computer has been recently rebooted. I think it's to try to keep people from clearing the intermittent codes or the ones that take a while to show up and pass. Some scanners will tell you if it is "ready" the cheaper ones do not.

Dhaka

Yes, i did rest the codes with a scanner from AutoZone, but Georgia's emission computer found it unready, so I have been told to drive a week or so. My Lexus dealer told me that I need to keep half-a-tank of gas overnight for a few nights and start with that amount every morning, and the computer will reset. I wonder why?

I have another question: I had changed a bulb with a similar bulb from Toyota, but the check bulb light comes on every time I shift into gear. Does anyone know why? How can I get rid of that pesky dashboard light? Thanks.

salimshah

I answered your gas tank part in my post #2 of this thread (low evap). With the gas cap on, the fuel delivery system must be able to contain vapors inside and if there is a leak then you fail this check.

"a bulb" ??? Please find out which bulb (check owner's manual) and search. Post in the appropriate thread or if it is a unique problem start another one.

Salim

scuz75

Drive cycles to reset readiness monitors. https://www.ih8mud.com/tech/tsb/LexusLX450/eg002l02.pdf