Ford Windstar 1996, DTCs P0151, P0161, P0171, and P0174

I have a 1996 Ford Windstar. I am getting DTCs as follows: P0171-System to lean, Bank 1, freeze frame; P0174-System to lean, Bank 2; P0141-02 Heater Circuit, Bank 1, Sensor 2; and P0161-02 Heater Circuit, Bank 2, Sensor 2. Could these 4 codes all be related to the same problem? If so, what could the possible solutions be? Also, where is the Bank 1, Sensor 2 and the Bank 2, Sensor 2 Oxygen Sensors located? Also, which set of cylinders is the Bank 1 set? Any help would be greatly appreciated.

Most likely you have a vaccum leak from the intake manifold! Very common, lots of tsbs out there about it!

I can understand why an intake manifold leak would cause the engine to run to lean but why would it cause the P0141 and P0161 DTCs?

Check the fuse as well as the circuit for the HO2s.

They're both located behind (downstream) of the cats.

The last poster said " they're both lcoated behind (downstream) of the cats." Is "both" referring to the oxygen sensors." Is "behind (downstream) of the cats" referring to the oxygen sensors being downstream of the catalytic converter or should I say between the catalytic converter and the back of the vehicle.




They're both located behind (downstream) of the cats

Your van has two converters, one is for bank1 and the other is for bank 2. Looking at it and if you are not familier it can be difficult to tell because Ford puts the connectors close together and space is limited. If you locate both converters the O2 sensors in question are the ones AFTER or BEHIND the converter.

Bank 1 is passenger side of engine. Non operating o2 heater circuits, will cause bad o2 sensor readings if not operating at correct temp. Check the heater circuits for power, sounds like you have an electrical problem. OBD2 tests HEGO sensor heaters in the non-continuous monitor test. A good scan tool will read these test results. If they fail then you have either blown heaters or bad wiring/power interruption or short (I'd suspect the latter).