Questions and Answers

Ford Ranger Has Many DTCs Q. I have a 1997 Ford Ranger with 97,000 miles. 2WD, 2.3 liter engine and automatic transmission. I have had codes P0171, P1130, P1131 and, the latest, P0133. They have been there for about 1½ years now. I have put a new fuel filter, fuel pump, fuel regulator, Throttle Position Sensor, Coolant Temperature Sensor, PCV valve, checked for vacuum leaks, gas cap leaks, intake gasket, and after reading your site a new Mass Air Flow sensor.

After putting the Mass Air Flow sensor on I still got the P1131 code. About the only thing left is my O2 sensor. The only real problem It gives me is when it's cold outside It will start but I have to hold it at half throttle for a few seconds then it will rev up and run fine. This thing is driving me nuts, any help would be greatly appreciated.

Thank you,
Eric

A. Lets look at what the codes are first.

DTC P0171 "Indicates the air/fuel mixture ratio is too lean". The fuel trim system is at the rich correction limit".

DTC P0133, P1130 and P1131 are all the same and "Indicates the response rate of the upstream Heated Oxygen Sensor (HO2S) is below some calibrated window". DTC P0133 refers to HO2S-11.

With these DTCs, the chances of the front HO2S being bad are fairly high.