P0172 Code What Does It Mean?

[acoustic]

Hi All,

I own a 1999 RX300 and the vehicle has just started setting an OBDII code of P0172. What does this mean I have re-set it with my code reader twice in two weeks... Any help would be appreciated.

Thanks,

Acoustic

[riwyle]

Hi All,

I own a 1999 RX300 and the vehicle has just started setting an OBDII code of P0172. What does this mean I have re-set it with my code reader twice in two weeks... Any help would be appreciated.

Thanks,

Acoustic

I believe that is saying a fuel rich condition. The easiest and cheapest first step should be to clean, or have your mechanic clean, the MAF(mass air flow) sensor.It is a very easy procedure to do yourself, if you are so inclined. If you go to a dealer, do not let him talk you into replacement- insist on cleaning.

[AmFam]

172 is a rich condition.

If you had a vacuum leak it would be too lean so you can eliminate that as an issue.

Too rich can be caused by a leaking injector, defective fuel pressure regulator or as simple as a CTS (Coolant Temp Sensor) being defecting. If it is a defective CTS what happens is, it tells the ECM that it is cold even when it is not. As a result, it allows much more fuel to pass thru the injectors.

As noted a MAF can cause it but normally if the MAS is bad it creates a poor running condition as well

[arens]

It could also be a pre-cat O2 sensor sending a bad signal. This sensor direclty affects the A/F ratio and can cause a rich or lean condition. Normally you will get codes directly relating to the O2 sensor being bad but I have seen similar instances of this happening.