Top 10 2005 Chevrolet Cobalt Questions & Answers

there is no way you can check the transmission you must take it to the dealer.that is what i was told

It sounds like you have a misfire. Anytime a misfire is detected by the powertrain control module (PCM) it flashes the check engine light (CEL) on and off. Do not drive it this way because it won't take long to damage the catalytic converter. Have the diagnostic trouble code (DTC) read with a scan tool or "code reader" to see what DTC or DTCs are set. If it's a 4 cylinder, it will have a P0301 set for a cylinder # 1 misfire, a P0302 for a cyl # 2 misfire & so on. If the misfire is random (ocurring in multiple cylinders intermittently) it will have a P0300 set. Once you know which cylinder is misfiring you can check that cyl to see what the cause might be. It could be an ignition coil or spark plug failure. The # 1 cyl is always the one closest to the front of the eng or this car, the one closest to the passenger side fender.

There are only 2 things you can try to fix this yourself: turn off the engine and open the driver side door (to turn the radio off). Wait 5 minutes, start your car.
If that does not solve it, turn off your engine, disconnect the car battery, wait about 5 minutes. Reconnect the battery (negative pole first - black connector) and try your radio again.

If neither one of these two fix your problem, I am afraid only a GM service center or dealership can fix the problem. The Cobalt is notorious for all kinds of electrical issues.

Thanks for using the fixya forums!

flip the diagram around it is upside down for some reason

Could be a problem in the shiftier. Your car doors lock automatically when you put the car in drive. They unlock when you put the car in park. The switch located in the shiftier can go bad causing the locks to randomly lock and unlock. Also, this can cause the key to get stuck in the ignition.

P0420 - Catalyst System Efficiency Below Threshold (Bank 1)
The catalytic converter has an oxygen sensor in front and behind it. When the vehicle is warm and running in closed loop mode, the upstream oxygen sensor waveform reading should fluctuate. The downstream O2 sensor reading should be fairly steady. Typically the P0420 code triggers the Check Engine Light if the readings of the two sensors are similar. This is indicative of (among other things) a converter that is not working as efficiently as it should be (according to specs). It is part of the vehicle emissions system.

You will likely not notice any drivability problems, although there may be symptoms.

Causes: A code P0420 may mean that one or more of the following has happened:
Leaded fuel was used where unleaded was called for
An oxygen sensor is not reading (functioning) properly
The engine coolant temperature sensor is not working properly
Damaged or leaking exhaust manifold / catalytic converter / exhaust pipe
Retarded spark timing
The oxygen sensors in front and behind the converter are reporting too similar of readings


Some suggested steps for troubleshooting a P0420 error code include:
Check for exhaust leaks at the manifold, pipes, catalytic converter. Repair as required.
Use a scope to diagnose the oxygen sensor operation (Tip: The oxygen sensor in front of the catalytic converter normally has a fluctuating waveform. The waveform of the sensor behind the converter should be more steady).
Inspect the downstream heated oxygen sensor (HO2), replace if necessary
Replace the catalytic converter

One thing to note is that many vehicle manufacturers offer a longer warranty on emissions-related parts. So if you have a newer car but it's out of it's bumper-to-bumper warranty, there still may be warranty on this type of problem. Many manufacturers give a five year, unlimited mileage warranty on these items. It's worth checking into.

Hope this helps (remember to rate and comment this answer).

Hi, there are 3 different engines for the 2005 Cobalt. I have pasted instructions from Autozone.com for all 3 below. I recommend you run the test also pasted below before buying a new sensor. If your sensor passes the test, please get back to me with your symptoms and/or trouble code for alternate repair advice. Please let me know if you have any questions, and thanks for using FixYa.
Removal & Installation2.0L Engine
Supercharger Inlet Pressure (Scip) Sensor

Fig. Manifold Absolute Pressure (MAP) SCIP sensor location-2.0L engine

1. Disconnect the Supercharger Inlet Pressure (SCIP) sensor harness connector.
2. Remove the SCIP sensor (1) from the supercharger.
   WARNING: If the SCIP sensor seal is damaged, the SCIP sensor must be replaced.
   
3. Inspect the seal for damage.

To install:
NOTE: Use the new SCIP sensor seal provided with the new SCIP sensor.

1. Install the SCIP sensor (1) into the intake manifold. Tighten the bolt to 89 inch lbs. (10 Nm).
2. Connect the SCIP sensor harness connector.

Temperature Manifold Absolute Pressure (Tmap) Sensor

Fig. Manifold Absolute Pressure (MAP) TMAP sensor location-2.0L engine

1. Disconnect the Temperature Manifold Absolute Pressure (TMAP) sensor harness connector.
2. Remove the TMAP sensor from the intake manifold.
   WARNING: If the TMAP sensor seal is damaged, the TMAP sensor must be replaced.
3. Inspect the seal for damage.

To install:
NOTE: Use the new TMAP sensor seal provided with the new TMAP sensor.

1. Install the TMAP sensor into the intake manifold. Tighten the bolt to 89 inch lbs. (10 Nm).
2. Connect the TMAP sensor harness connector.

2.2L & 2.4L Engines

Fig. Manifold Absolute Pressure (MAP) sensor location-2.2L & 2.4L engines

1. Remove the throttle body.
2. Disconnect the engine harness electrical connector from the Manifold Absolute Pressure (MAP) sensor.
3. Remove the MAP sensor and seal.

To install:

1. Lubricate the NEW MAP sensor seal with clean engine oil.
2. Install the MAP sensor into the intake manifold.
3. Connect the engine harness electrical connector to the MAP sensor.
4. Install the throttle body.

Testing

1. Verify the integrity of the entire air induction system by inspecting for the following conditions:
   Any damage to, or hairline fractures of, the MAP sensor housing, Loose or improper installation, Any vacuum leak
2. Verify that restrictions do not exist in the MAP sensor port or vacuum source.
3. Determine the current vehicle testing altitude. Ignition ON, observe the scan tool BARO Sensor parameter.
4. Use the scan tool and compare the MAP Sensor parameter to a known good vehicle, under various operating conditions.

Circuit Testing

Fig. Manifold Absolute Pressure (MAP) connector end view-2.0L & 2.2L engines

Fig. Manifold Absolute Pressure (MAP) connector end view-2.4L engine

NOTE All electrical components and accessories must be turned OFF, and allowed to power down.

1. With the ignition OFF, disconnect the MAP harness connector at the MAP sensor.
2. Test for less than 5 ohms of resistance between the low reference circuit terminal 2 and ground-2.0L & 2.2L (A and ground-2.4L).
   1. If greater than the specified range, test the low reference circuit for an open/high resistance.
   2. If the circuit tests normal, replace the ECM.
3. With the ignition ON, test for 4.8-5.2 volts between the 5 volt reference circuit terminal 1 and ground-2.0L & 2.2L (C and ground-2.4L).
   1. If less than the specified range, test the 5 volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
   2. If greater than the specified range, test the 5 volt reference circuit for a short to voltage. If the circuit tests normal, replace the ECM.
4. Verify the scan tool MAP sensor parameter is less than 1 kPa.
   1. If greater than the specified range, test the signal circuit terminal 3-2.0L & 2.2L for a short to voltage.
   2. If the circuit tests normal, replace the ECM.
5. Install a 3A fused jumper wire between the signal circuit terminal 3-2.0L & 2.2L and the 5 volt reference circuit terminal 1-2.0L & 2.2L. Verify the scan tool MAP sensor parameter is greater than 126 kPa.
   1. If less than the specified range, test the signal circuit terminal 3-2.0L & 2.2L for a short to ground or an open/high resistance.
   2. If the circuit tests normal, replace the ECM.
6. If all circuits test normal, test or replace the MAP sensor.

Component Testing

NOTE You must perform the circuit/system testing, in order to verify the integrity of the MAP sensor circuits, before proceeding with the component testing.

1. Turn ON the ignition, with the engine OFF, and remove the MAP sensor.
2. Install a 3A fused jumper wire between the 5 volt reference circuit terminal 1-2.0L & 2.2L and the corresponding terminal of the MAP sensor.
3. Install a jumper wire between the low reference circuit terminal 2-2.0L & 2.2L of the MAP sensor and ground.
4. Install a jumper wire at terminal 3-2.0L & 2.2L of the MAP sensor.
5. Connect a DMM between the jumper wire from terminal 3 of the MAP sensor and ground.
6. Install the J 35555 to the MAP sensor vacuum port. Slowly apply vacuum to the sensor while observing the voltage on the DMM. The voltage should vary between 0-5.2 volts, without any spikes or dropouts.
7. If the voltage is not within the specified range or is erratic, replace the MAP sensor.

https://www.fixya.com/cars/t10273871-looking_camshaft_position_sensor

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according to wiki.answers.com
"Chevy Cobalt has a sealed Automatic Transmission... no dip stick. Probably best to take it in to get service by trans shop if you think it needs changing or re-filling."
Or
"There actually isn't one. It's a sealed system. There is a cap to fill the transmission directly ontop of the transmission. If you need to check the level, lift the car in the air and there is a 11mm plug on the bottom of the transmission, With the car running (WARNING: THE CAR MUST REMAIN RUNNING WHILE PLUG IS OUT!!!!) take the plug out, the fluid should trickle out of the hole. If no fluid comes out add fluid. AGAIN DONT SHUT THE CAR OFF WHILE IT IS RUNNING OR ELSE FLUID WILL POUR OUT!"

You have no voltage at 15 amp fuel pump fuse in the under hood fuse/relay center ? There is a fuel pump relay also in same under hood fuse box. The fuel pump fuse gets power from the fuel pump relay. The ( PCM ) engine computer controls that relay, gives power or ground electronically to turn the relay on giving power to the fuel pump through the fuel pump fuse. You could have a bad relay or an anti-theft system problem . What engine does you vehicle have 2.0 L or 2.2 L the 2.0 L engine gets power differently to fuel pump .