2002 Acura RSX Emissions Light

The “emissions” light on the dash of my 2002 Acura RSX lights up when I run the heater in winter months. It only comes on when the heater is on. It is never on in the summer, and even when it is warmer outside and I have the heater on, it will turn off. The gas cap is not loose, and the car is otherwise in great condition. Is this something I need to worry about?

Have the fault codes downloaded from the ECU and post them here.

This car is old enough to need a new thermostat. That’s just a guess.
Post the fault code(s) and we won’t have to guess.

Or a cat converter. Or sparkplugs. etc. etc.

I was tempted to offer a WAG, but resisted. I suspect that the “when heater is on” is a “red herring”. I’m guessing that it’s directly related to the temperature outside. I’ve seen a “marginal” cat converter manifest itself as an intermittant light, “on” when the weather is cold and “off” when the weather is hot. Since the catalyst effectiveness is directly related to the temperature of the platinum-palladium, I changed the cat converter and the codes disappeared. BUT, I had codes suggesting a converter.

I’d personally like to see the codes before making any suggestions.

It is warm here this week, so I will have to get the light to come on again and then get someone to read the code for me, but I will post it as soon as I get it.

The computer stores the codes, even after the light goes out, until they’re cleared or the computer is reset by pulling a fuse or disconnecting the battery.
So get the computer scanned for codes

A month later, I finally got the code. It is P1167. Definition: AF sensor 1 heater circuit malfunction. Probable causes: 1) poor electrical connection, 2) excessive rich condition, 3) failed AF sensor.

Suggested interpretations? Thank you!

Failed mass airflow sensor. The MAF sensor is a heated device that measures tha anount of air flowing through by the amount of current it takes to keep the sensor hot.

The good news is that the AF sensor is in th einduction system, just aft of the air filter. It’s eays to change.

The code indicates there’s a problem with the Air/Fuel sensor or the oxygen sensor. Not the MAF sensor.


Oops. My bad.
Thanks for correcting me.

Indeed it references the heater circtuit for the O2 sensor. This doesn’t necessarily implicate the sensor itself as it may be a wiring issue. Turning the blower fan off/on in the car shouldn’t make any difference. But if you’re sure it does, then perhaps these things somehow share a ground or something & that ground is a problem - ?