Question about 1444 code and 02 sensor

[russc]

My '90 325is shows the 1444 no fault stomp code, but I'm getting some pretty bad mileage. Around 15-18L/100km in town, 10L/100km highway. That's about 13/23 MPG. Smells a *little* rich, and the plugs had some minor carbon buildup.

Just wondering if 02 sensors can go bad without registering a fault code.

[dnguyen1963]

Is your sensor original? If it is then replace it. An O2 sensor that is on its way out might not register a code.

[E30_fiend]

1444 means no codes.

[russc]

Is your sensor original? If it is then replace it. An O2 sensor that is on its way out might not register a code.

I'm the third owner, but I assume it's original. Thanks.

1444 means no codes.

Yep, that's why I'm asking. I'm wondering how far the sensor has to go out of spec before it throws a code.

[E30_fiend]

I would shoot more for bad ignition parts than the O2 sensor.

Bad ignition parts won't throw a code but they will cause you're motor to run inefficiently. That could be causing your bad gas mileage. Your O2 sensor could be going bad but still not bad enough to register a code. It just may not be able to work up to its original standard.

I would do an entire ignition tune up as well as change the O2 sensor.


Taylor

[jlevie]

The O2 sensor is a scheduled maintenance item with a replacement interval of 100mi/160km. An aged sensor will cause the engine to run rich.

[TurboJake]

Yes, an 02 sensor can cause go bad without throwing a code. But if it's on its way out, generally it's bad fuel economy across the board.

However, a bad fuel pressure regulator can cause bad in town mileage while leaving the highway mileage relatively intact.

A vacuum leak can cause this too.

Neither of these will throw a code.

I'd start at checking for vacuum leaks, and then fuel pressure before jumping to the o2 sensor.

[russc]

a bad fuel pressure regulator can cause bad in town mileage while leaving the highway mileage relatively intact.

A vacuum leak can cause this too.

Neither of these will throw a code.

I'd start at checking for vacuum leaks, and then fuel pressure before jumping to the o2 sensor.

Great, thanks for the help. I didn't realize the FPR would leave okay highway driving mileage.