# Engine lights **URL:** \ **Category:** Maintenance/Repairs\ **Tags:** lexus, 300\ **Created:** [August 19, 2009, 4:35pm UTC](https://community.cartalk.com/t/engine-lights/35281 "2009-08-19T16:35:33Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![kandok](https://avatars.discourse-cdn.com/v4/letter/k/f0a364/32.png) [@kandok](https://community.cartalk.com/u/kandok)\ **Post date:** [August 19, 2009, 4:35pm UTC](https://community.cartalk.com/t/engine-lights/35281/1 "2009-08-19T16:35:33Z")
RE: 1999 Lexus ES VSC and Check Engine lights came on. Mechanic replaced air sensors. Lights came on again after a short period of time. Mechanic said catalytic converter needs replacing. Went to Lexus dealer and they confirmed rear catalytic converter need replacing. Replaced c.c. with after market c.c. Lights came on after a short period of time. Mechanic cleaned air sensor. Lights came on after a short period of time. Mechanic offered, at no charge, to check it on his computer again. Is there a problem with a sensor or on board computer figuring out the oxygen and fuel mixture? Is there a danger of massive repairs if this is not fixed? Ken in Oregon ---
**Author:** ![VDCdriver](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/vdcdriver/32/30_2.png) [@VDCdriver](https://community.cartalk.com/u/VDCdriver)\ **Post date:** [August 19, 2009, 4:45pm UTC](https://community.cartalk.com/t/engine-lights/35281/2 "2009-08-19T16:45:43Z")
Have the evaporative emissions system checked. While this is definitely counterintuitive, I can tell you from experience that a combination of the Stability Control warning light and the CEL can indicate a problem (solenoid valve, carbon canister) in the evap system, and this has been misdiagnosed by mechanics on more than one occasion. If you need a solenoid valve in the evap system replaced, that is relatively cheap. Replacement of a carbon canister can easily run $400, but even that is considerably less expensive than a new cat converter. ---
**Author:** ![kandok](https://avatars.discourse-cdn.com/v4/letter/k/f0a364/32.png) [@kandok](https://community.cartalk.com/u/kandok)\ **Post date:** [August 19, 2009, 7:11pm UTC](https://community.cartalk.com/t/engine-lights/35281/3 "2009-08-19T19:11:37Z")
Very informative. Thank you