P1074- Cannot Find Source Of Problem

[diverchris]

Help needed.

I purchased a 2005 RX330(Canadian built not Japanese) in April of this year. I love my RX. I bought it with 80 000 kms and now it has 102 000 kms (60 000 miles). All scheduled maintenance has been done and all I use is premium fuel.

However, I’ve been having some trouble and need some help.

Since July 14th, my VSC and check engine light come on.

The code is P1074- bank 2 running too lean

This has happened a total of 5 times now.

Since the diagnosis, the problem has not been identified. On the third scan the fault code P1074 appeared as well as the code indicating the B2S2 sensor needed to be replaced. I watched the engine scan and I could clearly see that B2s2’s readings were very low. All of the other sensor on the scan tool were reading 1.0 to 1.1 while B2S2 was reading 0.61 to 0.7.

Upon seeing this, B2S2 was replaced with a genuine Toyota/Lexus sensor. However, the same day the sensor was replaced the P1074 code re-appeared. However a scan and diagnosis could once again could not the problem.

If I do not get the error code cleared, via the scanning tool- it would take 5 start-up and the check engine on VSC light would disappear.

Out of all of the 5 times in which the lights come on I have found the following situations:

The engine light comes on within 5 minutes of the engine being turned on. Two out of the 5 times, the light came on while in stop and go traffic. The other three times the light came on during acceleration onto the highways(Interstate).

Last night Lexus scanned the errors(P1074), they were not able to locate the source of problem, ie mass flow sensor, rad temperature sensors, and the rest of the other possible problems associated with the P1074 code . Also during the scan, all of the sensors were reading fine,

To this end, no one has the solution. Now I’m reaching out for people who may have experience this frustration and what was the solution. Or alternatively, problem solvers who could help me. I have a long road trip planned and this is not very comforting

[joe913]

I have had similar issues. I checked the sensors--all okay. I was reading this forum and came across some instances of the fuel cap not sealing resulting in CEL, VSC, etc. lights showing. Some have wrapped teflon tape around the cap, under the o-ring seal. They also said to make sure you turn the cap until you hear a couple of clicks. I just replace the cap... so far, all is well. Good luck! :)