Hi Jim, Diagnostic Trouble Code (DTC) P0141
Rear Heated Oxygen Sensor Heater Malfunction
Circuit Description
The engine control module (ECM) supplies a voltage of about 450mm volts between the ECM terminals 14 and 16. The oxygen (O2) sensor varies the voltage within a range of about 1volt if the exhaust is rich, down to about 100mm volts if the exhaust is lean. The O2 sensor is like an open circuit and produces no voltage when it is below 360°C(600°F). An open O2 sensor circuit or a cold O2 sensor causes "open loop" operation.
Conditions for Setting the DTC
The heated O2 sensor heater resistance is less than 0 Ù or greater than 160 Ù. (1.4L DOHC)
The heated O2 sensor heater resistance is less than 10 Ù or greater than 30 Ù. (1.6L DOHC)
Action Taken When the DTC Sets
The Malfunction Indicator Lamp (MIL) will illuminate after three consecutive trip with a fail.
The ECM will record operating conditions at the time the diagnostic fail. This information will be stored in the Freeze Frame and Failure Records buffers.
A history DTC is stored.
The coolant fan turns ON.
Conditions for Clearing the MIL/DTC
The MIL will turn off after four consecutive ignition cycles in which the diagnostic runs without a fault.
A history DTC will clear after 40 consecutive warm up cycles without a fault.
DTC(s) can be cleared by using the scan tool.
Disconnecting the ECM battery feed for 10 seconds.
Diagnostic Aids
Normal scan tool voltage varies between 0.1volts and 0.9 volts while in closed loop.
Inspect the oxygen (O2) sensor wire. The O2 sensor may be positioned incorrectly and contacting the exhaust manifold.
Check for an intermittent ground in the wire between the O2 sensor and the engine control module.
Perform an injector 2alance test to determine if a restricted fuel injector may be causing the lean condition.
Vacuum of crankcase leaks will cause a lean running condition.
An exhaust manifold gasket leak of a cracked exhaust manifold may cause outside air to be pulled into the exhaust and past the sensor.
DTC P0141 - Rear Heated Oxygen Sensor Heater Malfunction
Step Action Value(s) Yes No
1 Perform an Euro On-Board Diagnostic (EOBD) System Check.
Is the system check complete? - Go to Step 2 Go to
"On-Board Diagnostic System Check"
2 Turn the ignition switch to LOCK.
Disconnect the Heated O2 sensor connector and engine control module (ECM) connector.
Check the Heated O2 sensor heater wire between the Heated O2 sensor connector terminal 3 and ECM connector terminal 16 for an open or short to ground.
Is the problem found? - Go to Step 3 Go to Step 4
3 Repair the wire of the connector terminal as needed.
Clear the DTCs from the ECM.
Road tests the vehicle.
Perform the diagnostic system check.
Is the repair complete? - System OK -
4 Turn the ignition switch to LOCK.
Replace the Heated O2 sensor.
Road tests the vehicle.
Perform the diagnostic system check.
Is the replacement complete? - Go to Step 6 -
5 Check if any additional DTCs are set.
Are any DTCs displaced that have not been diagnosed? - Go to applicable DTC table System OK
Diagnostic Trouble Code (DTC) P0481
High Speed Cooling Fan Relay Circuit Fault (1.6L DOHC)
Circuit Description
Ignition voltage is supplied directly to the cooling fan relay coil. The engine control module(ECM) controls the relay by grounding the control circuit via an internal switch called a driver. The primary function of the driver is supply the ground for the component being controlled. Each driver has a fault line which is monitored by the ECM. When the ECM is commanding a component ON, the voltage of the control circuit should be low (near 0volts). When the ECM is commanding the control circuit to a component OFF, the voltage potential of the circuit should be high(near battery voltage). If the fault detection circuit senses a voltage other than what is expected, the fault line status will change causing the DTC to set.
The relay is used to control the high current flow to the cooling fan motors. This allows the ECM driver to only have to handle the relatively low current used by the relay.
Conditions for Setting the DTC
The high speed cooling fan control circuit is an open or a short to battery or a short to ground condition exist.
Action Taken When the DTC Sets
The Malfunction Indicator Lamp (MIL) will not illuminate.
The ECM will store conditions which were present when the DTC was set as Failure Records data only.
This information will not be stored in the Freeze Frame data.
Conditions for Clearing the MIL/DTC
A history DTC will clear after 40 consecutive warm-up cycles without a fault.
DTC(s) can be cleared by using the scan tool.
Disconnecting the ECM battery feed for more than 10 seconds.
Diagnostic Aids
Using Freeze Frame and/or failure records data may aid in locating an intermittent condition. If the DTC cannot be duplicated, the information included in the Freeze Frame and/or failure records data can be useful in determining how many miles since the DTC set. The fail counter and Pass Counter can also be used to determine how many ignition cycles the diagnostics reported a Freeze Frame conditions (rpm, load, vehicle speed, temperature, etc.) that .are noted. This will isolate when the DTC failed.
DTC P0481 - High Speed Cooling Fan Relay Circuit Fault (1.6L DOHC)
Step Action Value(s) Yes No
1 Perform an Euro On-Board Diagnostic (EOBD) System Check.
Is the system check complete? - Go to Step 2 Go to
"On-Board Diagnostic System Check"
2 Turn the ignition switch to ON with the engine OFF.
Install a scan tool.
Command the relay ON and OFF.
Does the relay turn ON and OFF when commanded? - Go to Step 3 Go to Step 5
3 Turn the ignition switch to LOCK.
Disconnect the engine control module (ECM) connector.
Turn the ignition switch to ON.
Using a digital voltmeter(DVM), measure the current in high speed relay control circuit, at terminal 9 to ground for 2 minutes.
Does the amperage measure less than the specified value? 0.75 amps Go to
"Diagnostic Aids" Go to Step 6
4 Turn the ignition switch to LOCK.
Disconnect the relay.
Using a DVM, measure the resistance between terminals 85 and 9 in the high speed cooling fan relay control circuit in the ECM harness connector to ground.
Does the DVM display infinite resistance? - Go to Step 12 Go to Step 10
5 Turn the ignition switch to LOCK.
Disconnect the relay.
Connect a test light between the relay coil terminals 86 and 85 in the relay harness connector.
Turn the Turn the ignition switch to ON.
Using the scan tool, command the relay ON and OFF.
Does the test light turn ON and OFF with each commanded? - Go to Step 8 Go to Step 6
6 With the test light connected to ground, probe the ignition feed circuit in the relay harness connector.
Does the test light illuminate? - Go to Step 7 Go to Step 11
7 Turn the ignition switch to LOCK.
Reconnect the relay.
Disconnect the ECM connector containing the relay control circuit.
Turn the Turn the ignition switch to ON.
With a fused jumper wire connected to ground, probe the relay control circuit at terminal 9 in the ECM harness connector.
Does the relay operate? - Go to Step 9 Go to Step 10
8 Check the connections at the relay.
Is a problem found and corrected? - Go to Step 14 Go to Step 12
9 Check the connection at the ECM.
Is a problem found and corrected? - Go to Step 11 Go to Step 13
10 Repair the faulty relay control circuit.
Is the repair complete? - Go to Step 14 -
11 Repair the faulty relay ignition feed circuit.
Is the repair complete? - Go to Step 14 -
12 Replace the relay.
Is the replacement complete? - Go to Step 14 -
13 Replace the ECM.
Is the replacement complete? - Go to Step 14 -
14 Using the scan tool, clear the Diagnostic Trouble Codes (DTCs).
Start the engine and idle at normal operating temperature.
Operate the vehicle within the conditions for setting the DTC as specifiec in the supporting text.
Does the scan tool indicate that this diagnostic ran and passed? - Go to Step 15 Go to Step 2
15 Check if any additional DTCs are set.
Are any DTCs displayed that have not been diagnosed? - Go to
Applicable DTC
table System OK
on August 16, 2007, 8:50 pm, in reply to "Daewoo Nubira 20021.6 DOHC A16DM"