Check engine light on

Tiny
DJDIVINE
  • MEMBER
  • 2002 PONTIAC GRAND AM
  • 4 CYL
  • 2WD
  • MANUAL
I have a 2002 Pontiac Grand Am 2.2L. The check engine light is on. When diagnosed it said the o2 sensor was bad post cat converter. The part was replaced and light reset but light came back on. When diagnosed again it said the o2 sensor was still bad. Is there something else that needs to be replaced?
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Saturday, March 19th, 2011 AT 2:22 PM

4 Replies

Tiny
SATURNTECH9
  • EXPERT
Lets start with what the exact code number you have?Then we will go from there.
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Saturday, March 19th, 2011 AT 5:06 PM
Tiny
DJDIVINE
  • MEMBER
The codes read as follows. P0141 and P0440. There are also 2 other codes which are pending with the same code numbers
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Sunday, March 20th, 2011 AT 9:23 PM
Tiny
SATURNTECH9
  • EXPERT
Your p0440 is a evap code and has nothing to do with the code P0141 I have posted the code description for P0440 below you would look for a loose gas cap or a seal on the gas cap that was cracking.A kinked or damaged canister purge solenoid or the hose to or from it a damaged vent valve or line to or from it. You might want to bring it to someone if your not familar with the evap system and it take's special tools to test them like a nitrogen cart scan tool with the correct software etc. Now for your code P0141 did you replace the o2 sensor in your exhaust manifold or the one down by your cat?I also posted the code description for code P0141.

SYSTEM DESCRIPTION
The control module tests the evaporative emission (EVAP) system for a large leak. The control module monitors the fuel tank pressure (FTP) sensor signal to determine the EVAP system vacuum level. When the conditions for running are met, the control module commands the EVAP canister purge valve OPEN and the EVAP vent valve CLOSED. This allows engine vacuum to enter the EVAP system. At a calibrated time, or vacuum level, the control module commands the EVAP canister purge valve closed, sealing the system, and monitors the FTP sensor input in order to determine the EVAP system vacuum level. If the system is unable to achieve the calibrated vacuum level, or the vacuum level decreases too rapidly, this DTC sets.

The table illustrates the relationship between the ON and OFF states, and the OPEN or CLOSED states of the EVAP canister purge and vent valves.

CONDITIONS FOR RUNNING THE DTC

* DTCs P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0122, P0123, P0125, P0452, or P0453 are not set.
* The ignition voltage is between 10-18 volts.
* The barometric pressure (BARO) is more than 75 kPa.
* The fuel level is between 15-85 percent.
* The engine coolant temperature (ECT) is between 4-30 C (39-86 F).
* The intake air temperature (IAT) is between 4-30 C (39-86 F).
* The start-up ECT and IAT are within 9 C (16 F) of each other.
* The vehicle speed sensor (VSS) is less than 121 km/h (75 mph).

CONDITIONS FOR SETTING THE DTC
The EVAP system is not able to achieve or maintain vacuum during the diagnostic test.

ACTION TAKEN WHEN THE DTC SETS

* The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
* The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

CONDITIONS FOR CLEARING THE MIL/DTC

* The control module will turn the malfunction indicator lamp (MIL) OFF during the first consecutive trip in which the diagnostic has been run and passed.
* A last test failed (current DTC) clears when the control module turns OFF the MIL.
* The history DTC will clear after the control module runs and passes 40 consecutive warm up cycles with no failure.
* The DTC can be cleared by using a scan tool.

DIAGNOSTIC AIDS

* Reviewing the Failure Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.
* Use the J 41413 EVAP Pressure/Purge Diagnostic Station in order to pressurize the EVAP system to aid in locating intermittent leaks. Move all EVAP components while testing with the J 41416 Ultrasonic Leak Detector.
* A temporary blockage in the EVAP canister purge valve, purge pipe, or EVAP canister could cause an intermittent condition. To repair a blockage in the EVAP system refer to Evaporative Emission (EVAP) System Cleaning.

CIRCUIT DESCRIPTION
Heated oxygen sensors (HO2S) are used for fuel control and post catalyst monitoring. Each HO2S compares the oxygen content of the surrounding air with the oxygen content of the exhaust stream. When the vehicle is first started, the powertrain control module (PCM) operates in an Open Loop mode, ignoring the HO2S signal voltage when calculating the air-to-fuel ratio. The PCM supplies the HO2S with a reference, or bias, voltage of 450 mV. The HO2S generates a voltage within a range of 0-1000 mV, that fluctuates above and below bias voltage once in Closed Loop. A high HO2S voltage output indicates a rich fuel mixture. A low HO2S voltage output indicates a lean mixture. A heating element inside the HO2S reduces the time required for the sensor to reach operating temperature, and provide an accurate voltage signal.

The HO2S heater diagnostic runs continuously when the heater circuit is energized. The HO2S heater circuit is only energized when the engine is running or commanded ON by the scan tool. The DTC will set if the heater current is above or below a calibrated threshold for 200 seconds.

CONDITIONS FOR RUNNING THE DTC

* The ignition 1 signal is more than 10 volts.
* The engine coolant temperature (ECT) is more than 45 C (113 F).
* The airflow is less than 40 g/s.
* The engine run time is more than 60 seconds.
* The HO2S 2 voltage is between 395-495 mV.

CONDITIONS FOR SETTING THE DTC
The HO2S 2 heater current is not within the calibrated range for more than 200 seconds.

ACTION TAKEN WHEN THE DTC SETS

* The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
* The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

CONDITIONS FOR CLEARING THE MIL/DTC

* The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
* A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
* A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
* Clear the MIL and the DTC with a scan tool.
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Monday, March 21st, 2011 AT 1:52 AM
Tiny
NGB5548
  • MEMBER
I have had this problem, and it turned out to be a leak in the intake manifold. For some reason, the car is extra sensitive and the codes for the O2 sensors kept showing up, even though the leak was very small (so small, that when I suggested it, they determined that wasn't the cause). It wasn't until my coolant had leaked out significantly (into the engine) that it was discovered. I hope this helps!
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Friday, March 25th, 2011 AT 2:48 AM

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