O2 Sensor and Evap “Not Ready”

Hello so I just bought this 2002 V8 with 190k miles off my father in law. He told me he didn’t want to deal with the truck anymore because of the problem it has. He can’t take it in to smog because the o2 sensor and the Evap are not ready. The check engine light is off and the truck throws no codes when checked with the OBD scanner. I bought brand new NTK oxygen sensors and replaced all 4. Still nothing and not ready to smog. I don’t know what else to do. Can someone please help.

 

Are there codes pending?

 

Have you followed the drive cycle procedure exactly?

https://m.smogtips.com/OnlineForumQ...oyota-Tundra-Drive-Cycle-to-Complete-Monitors

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Answer:




Sounds like your Toyota Tundra has had its emission monitors (also known as readiness flags) erased at some point while it was being worked on, either due to the battery being disconnected or trouble codes being cleared (which subsequently also erases Emission Monitors).

Driving your Toyota Tundra in order to make READY the emission monitors is correct, however a specific driving pattern, known as a Drive Cycle, must be followed in order to make the monitors ready, and allow your truck to pass the smog inspection.

The following Drive Cycle should set all the required emission monitors. Follow them carefully and as accurately as possible. Take extra caution when performing the drive cycle on public roadways. If you feel you will not be able to complete the driving pattern safely please seek assistance from a Toyota dealership. The dealer will be able to perform the drive cycle on a dynamometer, eliminating the need to drive the truck on streets and freeways.

Begin by: (It is very important to make sure your Toyota Tundra has only between 1/4 and 3/4 of fuel in the gas tank. Some of the monitors (particularly the EVAP monitor) will not run while your truck has any amount of fuel other than 1/4 to 3/4 tank.

• Start the engine. Idle the engine in drive for two and a half minutes with the A/C and rear defroster on.
• Turn the A/C and rear defrost off, and accelerate to 55 mph at half throttle.
• Hold at a steady speed of 55 mph for three minutes.
• Decelerate (coast down) to 20 mph without braking.
• Accelerate back to 55 to 60 mph at ¾ throttle.
• Hold at a steady speed of 55 to 60 mph for five minutes.
• Decelerate (coast down) to a stop without braking.

If all other emissions systems are functioning properly, completing the drive cycle above should set the emission monitors required to pass the smog test. We recommend performing the drive cycle 2 or 3 times before the smog inspection. Using a scan tool check which monitors have become ready after each drive cycle."

 

Never heard of this cycle before. Maybe explains why my rear o2’s tested at ZERO Ohms and never threw a CEL.

The Island has no ‘Smog’. Wonder if its worth doing the Reset Cycle because it doesn’t matter for testing? If it helps with the engine then I’ll do it.

 

It can sometimes be the craziest things to cause this problem. If you have a scan tool that can look at live data make sure that the coolant temperature is indicating correctly. I am not sure all the parameters for O2 and Evap on this model Tundra but I have seen a bad temp sensor for the ECM prevent the completion of the drive cycle parameters on other vehicles.

 

No codes pending.

 

I have the EXACT same issue with my 2005 Tundra 4x4 4.7 V8 with 157k miles. It had two check engine code and from what I read was a gas cap and possibly a vacuum issue. I replaced the gas cap and found the vacuum hose on the intake plenum off. The pinch hose clamp was very weak so I put a gear worm hose clamp on it. Then I disconnected the battery for 5 minutes. I then drove 100 miles and has the emissions place check it. The engine light never came back and there was no more codes for any issues but the evap system says not ready. So I drove it another hundred miles, came back and the evap system still shows not ready but yet still no engine lights and no codes. I found this thread and just performed the above twice and I'm headed back to the emissions place now to see if it works.