CEL 0201 code - Ignition Signal Circuit
08-20-2004, 11:21 PM
#1
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Join Date: Jun 2001
Posts: 147
CEL 0201 code - Ignition Signal Circuit
At 120K, I was getting a bit of hesitation when I mash hard on the gas. I changed spark plugs, air and fuel filter (all OEM). This didn't do anything for the hesitation. CEL came on at 125K, kicked codes 0304 (KS), and 0201 (Ign. Sig. Circuit). I changed the KS, so only code 0201 remains. The hesitation is still there. Sometimes while sitting at a stoplight, the car idles very rough, and seems like it will cut off (it's never cut off, though). Sometimes at 70-80 mph, the CEL light will flash for a few seconds, then it just stays on. Sometimes, when I mash hard, the car "putters" along as if the fuel line is clogged.
My question is: Could the hesitation be from Ignition Signal Circuit? Any help would be greatly appreciated. Thanks much in advance.
My question is: Could the hesitation be from Ignition Signal Circuit? Any help would be greatly appreciated. Thanks much in advance.
08-21-2004, 05:46 AM
#2
Replace coils.
0201
Diagnostic Trouble Code 0201 indicates a problem with the ignition coil and power transistor. The ignition signal from the Engine Control Module is sent to and amplified by the power transistor. The power transistor turns on and off the ignition coil primary circuit. This on-off operation induces the proper high voltage in the coil secondary circuit.
The malfunction is detected when the ignition signal in the primary circuit is not entered during engine cranking or running.
The items to check include
- Harness or connectors (the ignition primary circuit is open or shorted.)
- Power transistor unit built into ignition coil
- Condenser
- Crankshaft Position Sensor (REF)
- Crankshaft Position Sensor (REF) circuit
A misfire on any individual cylinder should set a code, and a problem with the CPS should also set a code.
I would have expected to see DTC 0201 along with one of the following DTCs.
0407 - Crankshaft Position Sensor (REF)
0608 - Cylinder 1 misfire
0607 - Cylinder 2 misfire
0606 - Cylinder 3 misfire
0605 - Cylinder 4 misfire
0604 - Cylinder 5 misfire
0603 - Cylinder 6 misfire
You didn't get one of these "companion" DTCs, and that is puzzling. Maybe one of them will show up in the next few days.
0603 0604 0605 0606 0607 0608
If one cylinder is misfiring the problem is spark or fuel. A misfire due to a spark problem usually results in a Service Engine Soon light and one of these Diagnostic Trouble Codes:
0608 - Cylinder 1 misfire
0607 - Cylinder 2 misfire
0606 - Cylinder 3 misfire
0605 - Cylinder 4 misfire
0604 - Cylinder 5 misfire
0603 - Cylinder 6 misfire
There are two tests the home mechanic can make, the sound test and the resistance test.
Sound test...
This test is performed with the engine idling. Use a mechanic's
stethoscope or a length of rubber vacuum hose, and listen to each injector.
All injectors should sound alike. If you find one which makes a different
sound (or no sound at all) you have found a problem.
Resistance test...
This test is performed with the engine off. Use an ohmmeter to measure the
resistance of each injector. This does not require removing the injectors.
I don't know the correct resistance value for the injectors on your model,
but they are typically a low number such as 16 ohms. The important thing
is they should all be equal. If you find one injector with substantially
higher resistance than the others, it is bad. If you find one with zero
ohms (short circuit) that is truly unfortunate, because the injector is bad
and it may also have damaged the Engine Control Module (the computer)
because of excessive current drain.
Measuring the resistance of the front bank of cylinders is easy because the
injectors are in plain view. Disconnect the injector electrical connector
for cylinder #2, measure the resistance, reconnect the connector. Repeat
for the cylinders #4 and #6.
Measuring the resistance of the rear bank of cylinders is almost as easy,
but it is difficult to reach the injectors. The resistance may be measured
at a conveniently located electrical connector. Notice the largest,
thickest electrical harness at the top of the engine. This is the Engine
Control Harness and it is shaped like a U, with the open top of the U at the
driver's side of the car. The U has two corners. Look at the corner
nearest the passenger seat. Just inside that corner you will find an 8-pin
electrical connector. This is connector F131. Disconnect this
connector. Now look at the male part, the connector half with the pins
exposed. They are arranged in two rows of four pins.
The pins are numbered 1 - 4 (top row) and 5 - 8 (bottom row).
Measure the resistance of:
- injector #1 between pins 1 and 2.
- injector #3 between pins 1 and 6.
- injector #5 between pins 1 and 5.
Be sure to measure the PINS, not the female receptacles.
The dealer's shop is equipped with high-tech diagnostic instruments. These are wonderful devices but they are expensive and the dealer has to recover his cost by charging you for diagnostic time. Sometimes the home mechanic can do legitimate diagnostic work with nothing more than a ohmmeter and a rubber tube.
To Test Ignition Coils:
With the ignition off, disconnect the electrical connector from the ignition coil. Connect the positive (+) probe of an ohmmeter to terminal no. 1 and the negative (-) probe to terminal no. 2 of the coil connector - the meter should indicate infinite resistance. Reverse the meter leads ( negative probe to terminal no. 1 and positive probe to terminal no.2) - the continuity should be indicated, but not zero ohms. If the results are not as specified, replace the coil.
Connect an ohmmeter between the secondary terminal ( the one that the spark plug connects to) and terminal no. 1 - the meter should indicate infinite resistance. If not, replace the coil.
Note - Ohm meter to test coils is not the most reliable way. Some peoples’ coils tested perfectly, but they still misfired.
0201
Diagnostic Trouble Code 0201 indicates a problem with the ignition coil and power transistor. The ignition signal from the Engine Control Module is sent to and amplified by the power transistor. The power transistor turns on and off the ignition coil primary circuit. This on-off operation induces the proper high voltage in the coil secondary circuit.
The malfunction is detected when the ignition signal in the primary circuit is not entered during engine cranking or running.
The items to check include
- Harness or connectors (the ignition primary circuit is open or shorted.)
- Power transistor unit built into ignition coil
- Condenser
- Crankshaft Position Sensor (REF)
- Crankshaft Position Sensor (REF) circuit
A misfire on any individual cylinder should set a code, and a problem with the CPS should also set a code.
I would have expected to see DTC 0201 along with one of the following DTCs.
0407 - Crankshaft Position Sensor (REF)
0608 - Cylinder 1 misfire
0607 - Cylinder 2 misfire
0606 - Cylinder 3 misfire
0605 - Cylinder 4 misfire
0604 - Cylinder 5 misfire
0603 - Cylinder 6 misfire
You didn't get one of these "companion" DTCs, and that is puzzling. Maybe one of them will show up in the next few days.
0603 0604 0605 0606 0607 0608
If one cylinder is misfiring the problem is spark or fuel. A misfire due to a spark problem usually results in a Service Engine Soon light and one of these Diagnostic Trouble Codes:
0608 - Cylinder 1 misfire
0607 - Cylinder 2 misfire
0606 - Cylinder 3 misfire
0605 - Cylinder 4 misfire
0604 - Cylinder 5 misfire
0603 - Cylinder 6 misfire
There are two tests the home mechanic can make, the sound test and the resistance test.
Sound test...
This test is performed with the engine idling. Use a mechanic's
stethoscope or a length of rubber vacuum hose, and listen to each injector.
All injectors should sound alike. If you find one which makes a different
sound (or no sound at all) you have found a problem.
Resistance test...
This test is performed with the engine off. Use an ohmmeter to measure the
resistance of each injector. This does not require removing the injectors.
I don't know the correct resistance value for the injectors on your model,
but they are typically a low number such as 16 ohms. The important thing
is they should all be equal. If you find one injector with substantially
higher resistance than the others, it is bad. If you find one with zero
ohms (short circuit) that is truly unfortunate, because the injector is bad
and it may also have damaged the Engine Control Module (the computer)
because of excessive current drain.
Measuring the resistance of the front bank of cylinders is easy because the
injectors are in plain view. Disconnect the injector electrical connector
for cylinder #2, measure the resistance, reconnect the connector. Repeat
for the cylinders #4 and #6.
Measuring the resistance of the rear bank of cylinders is almost as easy,
but it is difficult to reach the injectors. The resistance may be measured
at a conveniently located electrical connector. Notice the largest,
thickest electrical harness at the top of the engine. This is the Engine
Control Harness and it is shaped like a U, with the open top of the U at the
driver's side of the car. The U has two corners. Look at the corner
nearest the passenger seat. Just inside that corner you will find an 8-pin
electrical connector. This is connector F131. Disconnect this
connector. Now look at the male part, the connector half with the pins
exposed. They are arranged in two rows of four pins.
The pins are numbered 1 - 4 (top row) and 5 - 8 (bottom row).
Measure the resistance of:
- injector #1 between pins 1 and 2.
- injector #3 between pins 1 and 6.
- injector #5 between pins 1 and 5.
Be sure to measure the PINS, not the female receptacles.
The dealer's shop is equipped with high-tech diagnostic instruments. These are wonderful devices but they are expensive and the dealer has to recover his cost by charging you for diagnostic time. Sometimes the home mechanic can do legitimate diagnostic work with nothing more than a ohmmeter and a rubber tube.
To Test Ignition Coils:
With the ignition off, disconnect the electrical connector from the ignition coil. Connect the positive (+) probe of an ohmmeter to terminal no. 1 and the negative (-) probe to terminal no. 2 of the coil connector - the meter should indicate infinite resistance. Reverse the meter leads ( negative probe to terminal no. 1 and positive probe to terminal no.2) - the continuity should be indicated, but not zero ohms. If the results are not as specified, replace the coil.
Connect an ohmmeter between the secondary terminal ( the one that the spark plug connects to) and terminal no. 1 - the meter should indicate infinite resistance. If not, replace the coil.
Note - Ohm meter to test coils is not the most reliable way. Some peoples’ coils tested perfectly, but they still misfired.
08-21-2004, 05:59 AM
#3
if you need an injector, i ship them oem for $30 each. i only have 4 left. new ones cost around $85-116. pm me if you interested. if your MIL is flashing that means its sensing misfires in the engine. commonly a igniton coil and injector problem.
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