P0174 p0402 p1150 p1151 and p0401
Hi there:
P0401 OBD-II Trouble Code - 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.
Symptoms: You may notice drivability problems such as pinging (a.k.a. pre-ignition knock) when the engine is under load or the vehicle is at higher speeds. There may also be other symptoms.
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
P0402 OBD-II Trouble Code - Exhaust Gas Recirculation Flow (EGR) Excessive Detected
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 (DPF). These things work together to deliver the correct amount of recirculation based on engine temperature, load, etc. The P0402 code means that OBD detected an excessive amount of EGR.
Symptoms: You may notice drivability problems such as the engine may surge off idle. There may also be other symptoms.
A code P0402 most likely means one or more of the following has happened:
The DPFE (differential pressure) sensor is faulty and needs to be replaced
There is a blockage in the EGR (most likely carbon buildup)
The EGR valve is faulty
The EGR valve may not be opening due to a lack of vaccuum
Possible Solutions: with a P0402, it is common for people to replace the EGR valve, only to have the problem return. The most likely solution is to replace the DPFE sensor.
Check the voltage at the DPFE sensor both at idle and when the EGR is open
Replace the DPFE sensor
P1150 OBD-II Trouble Code - Air/Fuel Sensor Circuit Range/Performance (Bank 1 Sensor 2)
P1151 OBD-II Trouble Code - Lack of Upstream Heated Oxygen Sensor Switch - Sensor Indicates Lean - Bank No. 2
upstream is considered the oxygen sensor for the right side exhaust manifold, before the catalytic convertor. Make sure the sensor's electrical connection is in good condition. On the sensor, test between the terminals with an multimeter/ohmmeter. You should see about 6 ohms at 68*F. If not, replace.
The reason your engine is doing that is because the sensor is failing in such a way that the computer is dumping in extra fuel when it isn't really needed. Then you get the black smoke.
Hope this helps.
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