1999 Honda Accord uses more gas now that the check engine light is on

hi i have a hond accord from 1999 2l vtec engine. i have a chekengine that dous not go away. the first lambda voltage dous not change much 0.6v to 0.7v, the second lambda after cat dous varie wildly even when wharm. i have done a smoke test to find cracks/leaks, compression test was fine too. changed fuel filter and pump and both lambdas originals from honda. injectors seem fine to. The car drives normally, power is normal but i use a bit more gas then before the checkengine appeared.
the car has about 150000 km

Posting the check engine light code (ex. p0442) would be VERY useful in giving you accurate advice.

That being said, if the Air/Fuel Sensors (lambdas/ho2s sensors) stick, they can send a false signal causing excessive fuel mileage. But in general when the check engine light illuminates the engines computer receives a signal at the same time to use preset parameters in place of the once fluctuating signals. This in turn will cause higher fuel mileage until the repairs are made.

DRIVE CYCLE – AIR FUEL (A/F) RATIO SENSOR MONITOR – ACCORD, ALL 4-CYLINDER ENGINES

Notes:

1. If DTCs are erased, or power to the ECM interrupted, the readiness monitors will be set to Incomplete.
2. Do not turn ignition switch OFF during procedure.

Conditions:

1. Ambient temperature 20-95 degrees F.
   Steps:
2. To check if readiness codes are set, turn the ignition switch ON, but do not start the engine. The MIL will come ON for 15-20 seconds. If it goes OFF, readiness codes are set. If it blinks, readiness codes are not set.
3. Connect scan tool.
4. Start the engine and run it at 3000 rpm under no load in P or N, until the radiator fan comes ON.
5. Let the engine idle for 5 seconds.
6. Drive at a steady speed between 50-62 mph with A/T in D4 or M/T in 5th gear for 2 minutes.
7. With A/T in D4 or M/T in 5th gear, decelerate from 62 mph by completely releasing the throttle for at least 5 seconds. If the engine is stopped during this step, go back to Step 4 and start over.
8. Check the readiness status of the monitor with a scan tool.