Owners of the Toyota Camry and Corolla fill up message boards with one question. What do I do if my car says “not ready?” To answer the question, you must understand what the message means.
A Toyota Corolla/Camry “Not Ready To Drive” message means the onboard computer system hasn’t checked every aspect of the emissions control system for problems. The consequence of it is the onboard diagnostics system can’t determine if everything is working properly. Besides functioning poorly, your car will not pass an emissions test until it is “ready.“
What Does the OBD do?
The on-board diagnostics tool, a standard modern feature of today’s cars including those from Toyota, runs through all the parts of the emissions system to see if they are working. It also reports problems.
Specifically, the system completes up to 11 checks of components to the emission control systems. This includes the fuel systems, transmission, and engine.
Each element of the check communicates with a readiness monitor and these checks are done while the vehicle is driven, so that is why you must drive the car a certain number of miles to clear the light. This is called the “drive cycle.”
If everything is good, the computer messages that the systems are “ready.”Sometimes problems reported by the system are related to excessive exhaust emissions but they can also be linked to the car’s poor performance or poor fuel economy.
The Purpose and Problems of a “Not Ready” Message
The purpose of the message is to alert the driver there could be an emissions problem that needs to be fixed. The problem is the message isn’t always related to emissions. The additional problem is that you must wait to take the car to get an emissions inspection if the light is on.
Sometimes, the car won’t start at all with a “not ready” message but that could relate to an additional problem. One 2020 Camry owner reported her car only had 2,000 miles on it when the “not ready to drive” light came on. It died and only clicked when she tried to crank it.
In this driver’s case, the issue was a dead battery even though it was a new car.
Another driver of a 2001 Camry said the car said it wasn’t ready after the battery was replaced. They drove the car up to 800 miles and the light wouldn’t go off. He followed the suggested procedure of checking intake air and driving at both high and low speeds according to the Toyota manual but the light stayed on.
A possible problem, in this case, is the thermostat. Thermostats can stick causing temperature issues that that will cause the OBD to not work properly. It could also be a faulty coolant temp sensor.
What Would Cause a “Not Ready” Message?
Several factors contribute to a “not ready” message on your dashboard. Each of the potential issues is relatively easy and cheap to fix. They include:
- The car’s computer was reset during a recent repair or by a scan tool to look for codes.
- The computer had a software update that accidentally reset it.
- You or a mechanic disconnected the battery or it may have lost its charge. This can happen if you leave lights or accessories on for a long time.
- There is a true emissions control system problem so it can’t self-test.
When Should It Go Off?
It is typical for the “not ready” light to come on after a repair or after you replace a battery.
It can go away naturally after you’ve driven the vehicle between 30 and 100 miles at both highway and slower speeds.
The driving allows the “drive cycle” to go through a complete reset and also allows the sensors to recalibrate.
What Do I Do If It Doesn’t Reset?
Multiple options exist to resolve this problem. Here are some basic solutions to avoid taking it to a mechanic.
Check the Battery
The problem could be related to a bad battery or loose connections. Check the connections to make sure they are on tight. Check the voltage on the battery. Even a new battery can be a bad product and may not produce enough power.
If the car starts and the battery appears good, try running it through a drive cycle.
How to Run Through a Drive Cycle
Put some gas in your tank. It should be between 1/4 to 3/4 full. Then park your car for eight hours without starting it.
When the eight hours pass, start your car. Idle it in the drive gear for two and a half minutes. Be sure to run the air conditioning and the rear defroster.
After two and a half minutes, turn off both the air conditioning and the rear defroster. Drive the car for 10 minutes at highway speeds. Finally, drive the vehicle in stop-and-go traffic for 20 minutes. The “not ready” light should go off.
Doing this ensures that you are completing the required drive cycle as recommended by Toyota.
Different mechanics and state agencies have different recommendations for speeds, the amount of time driving, and idle times. Make sure your highway speed remains steady at between 40 to 70 mph and that you do it for at least three minutes but preferably up to 10. Some say it should be 15.
The engine speed should stay between 900 and 3,200 RPMs.
Everyone is consistent about driving in stop-and-go traffic for 20 minutes.When you stop for lights and stop signs, let it idle for 10 seconds to 30 seconds, even if the people behind you get annoyed. Some state there should be at least four idling times of at least 30 seconds.
A Problem With Garages
One of the problems with the “not ready” light is that garages erase the data when they are doing repairs. Clearing the data to get rid of the “check engine” light or disconnecting the battery will cause the “not ready” light to go on.
That’s because the computer reads checking these systems as “incomplete.” The problem with that is clearing the codes makes it impossible to predict when the computer monitors will be “ready.” In some cases, you may have to go through up to five drive cycles to make your car’s OBD system function properly so that the light goes off.
Experts state it could take two or three days of driving for a car to go through a complete cycle. It could take longer for older cars.
Government agencies, like the Environmental Protection Agency (EPA) in Ohio, are advising those who work on cars to not clear the Diagnostic Trouble Codes (DTCs).
This leaves the check engine light on. However, if the car was repaired correctly, the check engine light will turn off as you move through the drive cycle and OBD diagnostic runs through its check.
The “not ready” light isn’t a huge deal but does indicate something is going on with the computer diagnostics. It is up to you to determine if it’s related to a recent repair or a failed battery or if it is truly an emission issue.
Once you check the battery and have driven through the cycle a few times, it may be time to take the car to a garage to check for emission problems.