P0135 on second start?

[mikees67ss]

Ok I have very little hair left from pulling it out ........... 99 legacy 2.5. The CEL is activated on the SECOND START for the front o2 sensor. The CEL does not activate on the first start of the day. The ground is active and the voltage varies within range .3 to .45. Apparently the normal voltage is up to 1 volt so this looks ok to me. If anyone has any ideas about why the code appears on the second start please share your thoughts. I can't afford to lose any more hair. Thanks

 

[Falcon5]

What does voltage look like on the other bank during the same time period? You may have a vacuum leak. Any weird noises such as an exhaust leak? I would also look at mass airflow and check the air filter. Spark plugs look normal? Try a compression test to compare readings on all four cylinders?

 

[mikees67ss]

Voltages on rear 02, pin 24 .023, pin 37 .090 - .130, multi pin, (71. 13,14 etc) .004 - .012. Ground 56 seems good. no exhaust leak but it is a new cat, walker generic. Plugs look good and compression is within 10psi between cylinders. Vacuum leak, will check. Looks like I forgot to mention the code is p0135. Thank you for responding!