I have had some trouble with CEL for a few months. It flashed over a year ago, P0170 and P0173 came up, and local dealer tech told me I needed both rear O2 sensors. I lost confidence, cleaned the MAF, and had no problems for some time. In the past two months, CEL is back on, cleaned MAF again, but problem returned. I noted freeze data from my code reader and it seems that I may now need a new MAF. I hope the data below will confirm my guess, or another solution can be suggested. I have a few questions (most of the “newby” type) for the oracles, if they will indulge me:

What is the difference between FT 1, 2, 3, 4? Related to O2 sensors?

What is KPA units for data reported for MAP/ MAF?

How can I “reset” the ECU to begin the relearn process?

The STFT 1 and 2 seem within reasonable range and LTFT are at/outside the limits – does this indicate a recent change in conditions (MAF out of range)?

I already checked for vacuum leeks using the old starter fluid method – no leaks

The P0130, P0150 seem to be related to the MAF errors, based on other threads, any comments?

Thanks for any input – I’m at my limit of experience and knowledge


Freeze data from Actron CP9175

Date 7/15 7/17 7/19 7/20 7/21

Codes 170,173 170,173 170,173 170,173 170,173
130, 150

RPM 1875 600 575 575 550

Load 40.7% 22.7 23.1 23.1 23.1

MAP(KPA) 74 43 43 45 44

Coolant Temp 181 186 186 183 186

STFT 1 2.3% -1.0 -3.4 0.0 0.8

LTFT 1 28.9% 30.4 31.4 29.6 33.5

STFT 2 1.5% 0.8 -3.4 0.7 -1.0

LTFT 2 29.6% 31.2 32.0 30.4 34.3

STFT 3 -100.6 -100.6 -100.6 -100.6 -100.6

LTFT 3 -100.6 -100.6 -100.6 -100.6 -100.6

STFT 4 -100.6 -100.6 -100.6 -100.6 -100.6

LTFT 4 -100.6 -100.6 -100.6 -100.6 -100.6

MPH 43 0 0 0 0

Fuel Sys 1 Closed Closed Closed Closed Closed

Fuel Sys 1 Closed Closed Closed Closed Closed