Code p0401/ p0170/p0174/p0113 this code on my 1996 f-150 3.0 engine 5 speed 2 wheel drive
Hi there:
If the engine has no vacuum leaks next I
would check fuel quality and fuel pressure(41-47 psi key on engine off).
This could be low fuel pressure or even partially clogged injectors. GM
makes the best fuel injector cleaner I have used. We do the fuel
service with a pressure canister and include cleaning the throttle body
and induction service.
You could try that and as they do the service they can check the fuel pressure.
If
vacuum is OK, then hook up scan tool and observe 02 sensor signals,
good sensor will switch every second to above and below 0.45 milivolts.
P0171 - System Too Lean (Bank 1)
Basically
this means that an oxygen sensor in bank 1 detected a lean condition
(too much oxygen in the exhaust). On V6/V8/V10 engines, Bank 1 is the
side of the engine that has cylinder #1.
P0174 - System Too Lean (Bank 2)
Basically
this means that an oxygen sensor in bank 1 detected a lean condition
(too much oxygen in the exhaust). On V6/V8/V10 engines, Bank 2 is
generally the side of the engine that doesn`t have cylinder #1.
Note: This DTC is very similar to P0174, and in fact your vehicle may show both codes at the same time.
You
will more than likely not notice any drivability problems, although
there may be symptoms such as a lack of power, detonation (spark knock),
and/or a hesitation/surge on acceleration.
A code P0171 or P0174 may mean that one or more of the following has happened:
The
MAF (Mass Air Flow) Sensor is dirty or faulty. Note: The use of "oiled"
air filters may cause the MAF to become dirty if the filter is
over-oiled. There is also an issue with some vehicles where the MAF
sensors leak the silicone potting material used to protect the
circuitry.
There could be a vacuum leak downstream of the MAF sensor.
Possible solutions include:
In
the vast majority of cases, simply cleaning the MAF sensor does the
trick. Consult your service manual for it`s location if you need help. I
find it`s best to take it off and spray it with electronics cleaner or
brake cleaner. Make sure you are careful not to damage the MAF sensor,
and make sure it`s dry before reinstalling
Inspect all vacuum and PCV hoses, replace if necessary
Check for a dirty fuel filter and proper fuel pressure
P0401 - Insufficient EGR Flow
EGR stands for Exhaust Gas Recirculation. It is part of the vehicle emmissions system, and is used to reduce combustion temperature and pressure to control Oxides of Nitrogen. There are generally three parts to the EGR system: the EGR valve, an actuator solenoid, and a differential pressure sensor EGR (DPFE). These things work together to deliver the correct amount of recirculation based on engine temperature, load, etc. The P0401 code means that OBD detected an insufficient amount of EGR.
A code P0401 most likely means one or more of the following has happened:
The DPFE (differential pressure feedback EGR) sensor is faulty and needs to be replaced
There is a blockage in the EGR (tube), most likely carbon buildup
The EGR valve is faulty
The EGR valve may not be opening due to a lack of vaccuum
Possible Solutions;
In fixing this code, it is quite common for people to just replace the EGR valve only to have the OBD code return. The EGR valve is not always the culprit.
Use a vacuum pump and pull the EGR valve open while monitoring engine RPM's & DPFE voltage. There should be a noticable difference in RPM's with the EGR open
Clean out the EGR valve and/or tubing to remove deposits
Check the voltage at the DPFE, compare to specified values (refer to a repair manual for your specific model)
Replace the DPFE sensor (with a good quality / OEM one)
Replace the EGR valve
P0113 - Intake Air Temperature Circuit High Input
The powertrain control module (PCM) monitors the temperature of the air entering the engine. The PCM supplies a 5 volt reference voltage to the Intake Air Temperature (IAT) sensor. The IAT is a thermistor that varies resistance based on temperature. As the temperature increases, resistance decreases. Low temperature results in a high signal voltage. When the PCM sees a signal voltage higher than 5 volts, it sets this P0113 check engine light code.
There will likely be no symptoms other than illumination of the Malfunction Indicator Lamp (MIL - Check Engine Light / Service Engine Soon).
A code P0113 may mean that one or more of the following has happened:
Internally failed IAT sensor
Faulty connection at IAT sensor
Open in IAT ground circuit or signal circuit
Short to voltage in IAT signal circuit or reference circuit
IAT harness and/or wiring routed too close to high-voltage wiring (e.g. alternator, spark plug cables, etc.)
Faulty PCM (less likely but not impossible)
Possible Solutions:
First, if you have access to a scan tool, is there an IAT reading? If the IAT reading is logical then the problem is likely intermittent. If the reading is less than -30 degrees, unplug the connector. Install a jumper wire between the harness connector signal and ground circuits. The IAT temperature reading on the scan tool should be maxed out at the high end. For example it should be 280 degrees Farenheit or higher. If it is, the wiring is okay, and it may have been the connection. If it isn't install the jumper wire between the IAT signal circuit and the chassis ground.
If now the IAT reading on the scan tool is maxed out then check for an open in the IAT ground circuit. If you get no reading at all on the scan tool, it's likely that the sensor signal is open or the 5 volt reference is missing. Check using a DVOM (digital volt ohm meter) for a 5 volt reference. If it's there, then unplug the connector at the PCM and check for continuity on the IAT signal circuit between the PCM connector and the IAT connector.
Hope this helps.
Thanks for the info. I thought that may have been the sensor. It is plugged in and I do have voltage to the sensor as required. Sensor must be faulty. I've been reading some forums and I've read that the EGR valve could set the p1404 code, but it didnt make sense since the p1404 code says its the IAT sensor manfunction. Thanks for the tip.
Nate
×