Diagnosing DPFE Sensor (P0401 and P0402) with Scan Tool
Originally Posted by Sterling_Six
Please get back to us with the Codes...Thanks
Fords have an issue with their (Differential Pressure Feedback Exhaust Gas Recirculation [EGR]) DPFE Sensors. The DPFE sensor regulates how much exhaust runs back into the system for emissions reasoning.
Now, this is what it looks like:
Ford tried to fix the issue with a plastic DPFE:
They last just as long as the metal ones. The voltage for the sensor (which can be found under Live Data or Data Stream in a scan tool) should be around .55-1 volt at idle. Anything higher and it should be replaced.
If you can graph out engine vaccum and the voltages you're likely to see, it would look similar to this graph:
courtesy of rockledge
The most frequent codes with a DPFE sensor issue is a P0401 and/or a P0402. These mean following:
Exhaust Gas Recirculation Flow Insufficient Detected
Exhaust Gas Recirculation Flow Excessive Detected
Now with the scan tool (I used a NGS
on my last DPFE situation on a '01 Ranger 3.0L) you can verify your voltage at idle. The voltage I had was a little over 2 volts at idle. And I had the two above codes in the system - with only the 402 code coming on with KOER, but the P0401 was in continous/current codes.
If you unplug the sensor and the voltage reads 5.0 volts - then this means that your circuitry is good and that a sensor is needed.
Hopefully that helps some people.
Please go to this link also: http://ww2.justanswer.com/uploads/ad...t_monitors.pdf
Ford P0171 & P0174 Lean Codes
P0161 OBD-II Trouble Code
Oxygen O2 Sensor Circuit Low Voltage (Bank 2, Sensor 2)
What does that mean?
It basically means the PCM detected either an excessive current draw, or an open or short in the circuit powering the oxygen sensor's heater circuit. This is in reference to the Heated Oxygen Sensor (2) located rear of catalytic converter (Bank 2
There will likely be no obvious symptoms other than MIL illumination.
A code P0161 may mean that one or more of the following has happened:
- <LI itxtvisited="1">HO2S heater power circuit open <LI itxtvisited="1">HO2S heater ground circuit open <LI itxtvisited="1">HO2S signal tracking (due to oil or moisture in the connector)
- HO2S is damaged or has failed PCM has failed
- <LI itxtvisited="1">Replace HO2 Sensor <LI itxtvisited="1">Repair open or short in power circuit <LI itxtvisited="1">Repair open or short in ground circuit
- Repair damaged connector due to tracking