Codes 0901 and 0304
02-18-2004, 12:49 PM
#1
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Join Date: Apr 2002
Posts: 91
Codes 0901 and 0304
I got these two codes and I dont know exactly what to do about them. Do I have a short or something somewhere or are there some sensors that I need to replace. Any good imput is greatly appreciated.
02-18-2004, 12:56 PM
#2
0901
Diagnostic Trouble Code 0901 points to a problem with the Front Heated Oxygen Sensor, Right Bank. The right cylinder bank is also called the rear bank. It is cylinders 1,3,5.
The Front Heated Oxygen Sensors are installed in the Y-pipe, the part of the exhaust system which conveys exhaust gases from the exhaust manifolds to the Catalytic Converter. There is an Oxygen Sensor in each branch of the Y-pipe. These sensors produce a signal which varies with the concentration of oxygen in the exhaust gas, as compared to the outside air. This signal is sent to the Engine Control Module which uses it to control the fuel injection system.
DTC 0901 is detected when the current drawn by the heating element in the Oxygen Sensor is out of the normal range.
Possible causes include ...
- harness or connectors (the sensor circuit is open or shorted.)
- a defective Front Heated Oxygen Sensor (right bank).
The heated Oxygen Sensors have two components: a heating element and a sensing element. The heating element may be tested with an ordinary ohmmeter. This test is done with the engine off.
Follow the wires away from the Oxygen Sensor until you find the nearest electrical connector. Disconnect the connector. Viewed with the connector latch at the 12 o'clock position, there are three terminals. They are numbered 1-3, right to left. Be sure to measure the terminals in the connector half which is attached to the Oxygen Sensor, not the one which leads to the Engine Control Unit.
Measure the resistance between terminals 1 and 3.
The factory spec is 2.3-4.3 ohms at 77 degrees Fahrenheit.
Measure the resistance between terminals 1 and 2.
The reading should be infinity (no connection).
Measure the resistance between terminals 2 and 3.
The reading should be infinity (no connection).
If the resistance measurements are significantly different from the factory specifications the sensor is faulty and must be replaced.
If the resistance measurements meet the factory specifications the sensor may be good and the wiring is defective. You could exchange the two Front Heated Oxygen Sensors and reset the Engine Control Module. Then drive normally and expect the Malfunction Indicator Lamp to turn on again. If you still get DTC 0901 the wiring is faulty. If you get DTC 1001 the sensor is bad.
0304
Diagnostic Trouble Code 0304 points to a problem with the Knock Sensor. The KS is attached to the cylinder block. It senses engine knocking using a piezoelectric element. A knocking vibration from the cylinder block is senses as vibrational pressure. This pressure is converted into a voltage signal and sent to the Engine Control Module (The computer).
This malfunction is detected when an excessively high or low voltage from the KS is entered to the ECM. Possible causes include...
- the harness or connector (The KS circuit is open or shorted).
- the KS
The KS may be checked with an ohmmeter.
1) Raise the hood. View the engine from the driver's fender. Look into
the deep valley between the cylinder banks and below the intake manifold.
Identify the KS as a black item fastened to the block by a single vertical
bolt. A wire harness wrapped in black leads toward you, out of the valley.
That is the KS sub-harness.
2) Follow the KS sub-harness to it's nearest connector. This is connector F121.
It is located near the upper right-hand corner of the valve cover of the forward cylinder bank, as viewed from the front of the car.
3) Disconnect F121. You have to do a "press the latch and wiggle and
pull" to disconnect it. F121 has only two pins; if you see more than two
pins, you have the wrong connector. Use a digital ohmmeter capable of
measuring more than 10 Megohms. You want to measure the pins of F121, not
the sockets of the matching connector. Measure the resistance between a
good ground (such as the battery negative terminal) and pin #2 of connector
F121. On my car this is the highest of the two pins, the one closest to
the front of the car. The factory spec is 500 - 620 Kohms.
The manual says you have to remove the intake manifold to replace the KS. However, I think that a person with good dexterity and a 10mm ratcheting box wrench could replace the KS without disturbing the manifold.
Important note: the dealer can do a more thorough test with his CONSULT electronic tester. The resistance test described here is a useful but limited test. A Knock Sensor which fails this test is definitely bad. However, a KS which passes this test is not guaranteed to be good.
Diagnostic Trouble Code 0901 points to a problem with the Front Heated Oxygen Sensor, Right Bank. The right cylinder bank is also called the rear bank. It is cylinders 1,3,5.
The Front Heated Oxygen Sensors are installed in the Y-pipe, the part of the exhaust system which conveys exhaust gases from the exhaust manifolds to the Catalytic Converter. There is an Oxygen Sensor in each branch of the Y-pipe. These sensors produce a signal which varies with the concentration of oxygen in the exhaust gas, as compared to the outside air. This signal is sent to the Engine Control Module which uses it to control the fuel injection system.
DTC 0901 is detected when the current drawn by the heating element in the Oxygen Sensor is out of the normal range.
Possible causes include ...
- harness or connectors (the sensor circuit is open or shorted.)
- a defective Front Heated Oxygen Sensor (right bank).
The heated Oxygen Sensors have two components: a heating element and a sensing element. The heating element may be tested with an ordinary ohmmeter. This test is done with the engine off.
Follow the wires away from the Oxygen Sensor until you find the nearest electrical connector. Disconnect the connector. Viewed with the connector latch at the 12 o'clock position, there are three terminals. They are numbered 1-3, right to left. Be sure to measure the terminals in the connector half which is attached to the Oxygen Sensor, not the one which leads to the Engine Control Unit.
Measure the resistance between terminals 1 and 3.
The factory spec is 2.3-4.3 ohms at 77 degrees Fahrenheit.
Measure the resistance between terminals 1 and 2.
The reading should be infinity (no connection).
Measure the resistance between terminals 2 and 3.
The reading should be infinity (no connection).
If the resistance measurements are significantly different from the factory specifications the sensor is faulty and must be replaced.
If the resistance measurements meet the factory specifications the sensor may be good and the wiring is defective. You could exchange the two Front Heated Oxygen Sensors and reset the Engine Control Module. Then drive normally and expect the Malfunction Indicator Lamp to turn on again. If you still get DTC 0901 the wiring is faulty. If you get DTC 1001 the sensor is bad.
0304
Diagnostic Trouble Code 0304 points to a problem with the Knock Sensor. The KS is attached to the cylinder block. It senses engine knocking using a piezoelectric element. A knocking vibration from the cylinder block is senses as vibrational pressure. This pressure is converted into a voltage signal and sent to the Engine Control Module (The computer).
This malfunction is detected when an excessively high or low voltage from the KS is entered to the ECM. Possible causes include...
- the harness or connector (The KS circuit is open or shorted).
- the KS
The KS may be checked with an ohmmeter.
1) Raise the hood. View the engine from the driver's fender. Look into
the deep valley between the cylinder banks and below the intake manifold.
Identify the KS as a black item fastened to the block by a single vertical
bolt. A wire harness wrapped in black leads toward you, out of the valley.
That is the KS sub-harness.
2) Follow the KS sub-harness to it's nearest connector. This is connector F121.
It is located near the upper right-hand corner of the valve cover of the forward cylinder bank, as viewed from the front of the car.
3) Disconnect F121. You have to do a "press the latch and wiggle and
pull" to disconnect it. F121 has only two pins; if you see more than two
pins, you have the wrong connector. Use a digital ohmmeter capable of
measuring more than 10 Megohms. You want to measure the pins of F121, not
the sockets of the matching connector. Measure the resistance between a
good ground (such as the battery negative terminal) and pin #2 of connector
F121. On my car this is the highest of the two pins, the one closest to
the front of the car. The factory spec is 500 - 620 Kohms.
The manual says you have to remove the intake manifold to replace the KS. However, I think that a person with good dexterity and a 10mm ratcheting box wrench could replace the KS without disturbing the manifold.
Important note: the dealer can do a more thorough test with his CONSULT electronic tester. The resistance test described here is a useful but limited test. A Knock Sensor which fails this test is definitely bad. However, a KS which passes this test is not guaranteed to be good.
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