0140 0141 and
P0140 - 02 Sensor Circuit No Activity Detected (Bank 1 Sensor 2)
The Powertrain control module (PCM) will provide a .45 volt reference voltage to the Oxygen sensor. When the O2 sensor reaches operating temperature, it will generate a voltage that will vary depending on the oxygen content of the exhaust. Lean exhaust generates a low voltage (less than .45V) and rich exhaust generates a high voltage (greater than .45V). O2 sensors on a specific bank marked as "sensor 2" (as this one is) are used to monitor emissions. A Three-Way Catalyst (TWC) system (catalytic converter) is used to control tailpipe emissions. The PCM uses the signal received from Oxygen sensor 2 (#2 indicates aft of catalytic converter, #1 indicates pre-converter) to read efficiency of TWC. Normally this sensor will switch between high and low voltage at a noticeably slower rate than the front sensor. This is normal. If the signal received from rear (#2) O2 sensor indicates that the voltage has "stuck" between .425V to .474 V, the PCM determines this sensor is inactive and this code will set.
Potential Symptoms: Your check engine light(CEL), or malfuction indicator lamp (MIL) will be illuminated. There will not likely be any noticeable drivability problems other than the MIL. The reason is this: The rear or post catalytic converter Oxygen sensor does not affect fuel deliver(this is an exception on Chryslers). It only MONITORS the efficiency of the catalytic converter. For this reason, you will likely not notice any engine trouble.
Causes: The causes for a P0140 code are fairly few. They could be any of the following:
* Shorted heater circuit in O2 sensor. (Usually requires replacement of heater circuit fuse in fuse block also)
* Shorted signal circuit in O2 sensor
* Melting of harness connector or wiring due to contact with exhaust system
* Water intrusion in harness connector or PCM connector
* Bad PCM
Possible Solutions: This is a fairly specific problem and shouldn't be too difficult to diagnose.
First, start engine and warm up. Using a scan tool, watch the Bank 1, sensor 2, o2 sensor voltage. Normally the voltage should switch slowly above and below .45 volts. If it does, the problem is likely intermittent. You'll have to wait for the problem to surface before you can accurately diagnose.
However, if it doesn't switch, or is stuck then perform the following: 2. Shut off vehicle. Visually check the Bank1,2 harness connector for melting or chafing of the harness or the connector. Repair or replace as needed 3. Turn ignition on, but engine off. Disconnect the O2 sensor connector and check for 12Volts at the Heater Circuit supply and for proper ground on the heater circuit ground circuit. a. If 12V heater supply is missing, check the proper fuses for an open in the circuit. If heater circuit fuse is blown, then suspect a bad heater in the o2 sensor causing a blown heater circuit fuse. Replace sensor and fuse and recheck. b. If ground is missing, trace the circuit and clean or repair ground circuit. 4. Next, with connector still unplugged, check for 5 Volts on the reference circuit. If this is missing, check for 5 Volts at the PCM connector. If 5 Volts is present at the PCM connector but not at the o2 sensor harness connector, then there is an open or short in the reference wire supply between the PCM and the o2 sensor connector. However, if there is no 5 Volts present at the PCM connector, the PCM is likely at fault due to internal short. Replace PCM.
** (NOTE: on Chrysler models, a common problem is the 5Volt reference circuit can be shorted out by any sensor on the car that uses a 5 Volt reference. Simply unplug each sensor one at a time until the 5 Volts reappears. The last sensor you unplugged is the shorted sensor. Replacing it should fix the 5 Volt reference short.) 5. If all the voltages and grounds are present, then replace the Bank 1,2 O2 sensor and re-test.
P0141 - O2 Sensor Heater Circuit Malfunction (Bank 1, Sensor 2)
This code means that the heated circuit in the oxygen sensor on bank 1 decreases time needed to enter closed loop. As the O2 heater reaches operating temperature, the oxygen sensor responds by switching according to oxygen content of the exhaust surrounding it. The ECM tracks how long it takes for the oxygen sensor to begin switching. It the ECM determines (based on coolant temp) that too much time elapsed before the oxygen sensor began operating properly, it will set P0141. See also: P0135 (Bank 1, Sensor 1).
Symptoms: You will likely notice poor fuel economy the illumination of the Check Engine Light.
Causes: A code P0141 may mean that one or more of the following has happened:
* open or short to ground in the wiring harness
* O2 heater circuit wiring high resistance
* O2 heater element resistance is high
* Internal short or open in the heater element
Note: Typically a failed catalytic converter does not cause this code. You're more likely to see a P0420 code for a failed converter.
* Replace oxygen sensor (cannot repair open or short that occurs internally to sensor)
* Repair short or open or high resistance in wiring harness or harness connectors
P0339 - Crankshaft Position Sensor A Circuit Intermittent
The Crankshaft position sensor also known as the crank position sensor
is an electronic device used in an engine to record the rate at which
the crankshaft is spinning. This information is used by the Powertrain
Control Module (PCM) or Electronic Control Module(ECM) to control
ignition and fuel injection. The sensor system consists of a rotating
part, typically a disc, as well as a static part, the actual sensor.
When the engine is running, the high and low parts of the teeth cause
the gap with the sensor to change. The changing gap causes the magnetic
field near the sensor to change. The change in the magnetic field cause
the voltage from the sensor to change.
- The crankshaft position sensor (POS) signal sent to the ECM is intermittent
- The proper pulse signal from the crankshaft position sensor (POS) is not sent to Tech notes
- Sometimes and in some models, low battery voltage or a weak starter can can trigger a Crankshaft Position Sensor code.
- Engine Light ON (or Service Engine Soon Warning Light)
- Lack/Loss of Power
- Engine Stall
- Harness or connectors (The sensor circuit is open or shorted)
- Crankshaft position sensor may be faulty
- Signal plate may be damage
- Starter motor may be faulty
- Starting system circuit
- Dead (Weak) battery
- Charge battery
- Repair harness or connector
- Replaced Crankshaft Position Sensor.
I hope this helps to solve it (remember to rate this answer).
Jan 18, 2011 |
Porsche 911 Cars & Trucks