Dodge Ram Truck 1500-2500-3500. Manual — part 1170

P0141-O2 SENSOR 1/2 HEATER PERFORMANCE

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ENGINE - ELECTRICAL DIAGNOSTICS - SRT-10

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P0141-O2 SENSOR 1/2 HEATER PERFORMANCE (CONTINUED)

For the Engine circuit diagram (Refer to 9 - ENGINE - SCHEMATICS AND DIAGRAMS).

For a complete wiring diagram Refer to Section 8W.

Theory of Operation

This diagnostic provides a continuous check of the O2 heater circuit during operation. The heater circuit is momen-
tarily disabled to allow a resistance measurement to be taken to infer heater temperature. The current delivery to
the heater is duty cycled to maintain a specific target temperature. The error from the target temperature is contin-
uously monitored to assess heater performance.

•

When Monitored:
With battery voltage greater than 10.5 volts, at a cold start, ECT less than 147°F, battery temperature sensor
equal to or less than 27°F, and engine at idle for at least 12 seconds.

•

Set Condition:
O2 sensor voltage greater than 3 volts for 60 to 240 seconds.

Possible Causes

(K344) O2 SENSOR HEATER RELAY OUTPUT CIRCUIT OPEN

(K344) O2 SENSOR HEATER RELAY OUTPUT CIRCUIT SHORTED TO GROUND

(K127) O2 HEATER RELAY CONTROL CIRCUIT OPEN

(K127) O2 HEATER RELAY CONTROL CIRCUIT SHORTED TO GROUND

(Z1) HEATER GROUND CIRCUIT OPEN

O2 SENSOR

PCM

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING).

Diagnostic Test

1.

O2 SENSOR HEATER OPERATION

Turn the ignition off.

NOTE: Wait a minimum of 8 minutes to allow the O2 Sensor to cool down before continuing the test.
Ignition on, engine not running.

With the scan tool, actuate the O2 Heater Test.

With the scan tool, monitor O2 Sensor voltage for at least 2 minutes.

Does the voltage stabilize between 0.1 and 0.3 of a volt during the Heater test?

Yes

>> Refer to the INTERMITTENT CONDITION Diagnostic Procedure.

Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

No

>> Go To 2

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ENGINE - ELECTRICAL DIAGNOSTICS - SRT-10

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P0141-O2 SENSOR 1/2 HEATER PERFORMANCE (CONTINUED)

2.

O2 SENSOR HEATER ELEMENT

Turn the ignition off.

NOTE: Allow the O2 Sensor to cool to room temperature.
Disconnect the O2 Sensor harness connector.

Measure the resistance across the O2 Sensor Heater element component side.

NOTE: The resistance value will increase with warmer temperatures.

Is the resistance between 4.0 and 5.0 ohms at 70° F (21.1°C)?

Yes

>> Go To 3

No

>> Replace the O2 Sensor.

Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

3.

(K344) O2 SENSOR HEATER RELAY OUTPUT CIRCUIT

Ignition on, engine not running and the O2 Sensor still disconnected.

With the scan tool, actuate the O2 Heater Test.

Using a 12-volt test light connected to ground, probe the (K344) O2
Heater Relay Output circuit at the O2 Sensor harness connector.

Does the light illuminate brightly?

Yes

>> Go To 4

No

>> Repair the open or short to ground in the (K344) O2

Heater Relay Output circuit.

Perform the POWERTRAIN VERIFICATION TEST. (Refer
to 9 - ENGINE - STANDARD PROCEDURE)

4.

(K127) O2 HEATER RELAY CONTROL CIRCUIT OPEN

Turn the ignition off.

Disconnect the PCM harness connectors.

Remove the O2 Heater Relay.

Measure the resistance of the (K127) O2 Heater Relay Control circuit from the O2 Heater Relay to the PCM har-
ness connector.

Is the resistance below 5.0 ohms?

Yes

>> Go To 5

No

>> Repair the excessive resistance in the (K127) O2 Heater Relay Control circuit.

Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

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ENGINE - ELECTRICAL DIAGNOSTICS - SRT-10

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P0141-O2 SENSOR 1/2 HEATER PERFORMANCE (CONTINUED)

5.

(K127) O2 HEATER RELAY CONTROL CIRCUIT SHORTED TO GROUND

Measure the resistance between ground and the (K127) O2 Heater
Relay Control circuit at the PCM harness connector.

Is the resistance below 100 ohms?

Yes

>> Repair the short to ground in the (K127) O2 Heater Relay

Control circuit.

Perform the POWERTRAIN VERIFICATION TEST. (Refer
to 9 - ENGINE - STANDARD PROCEDURE)

No

>> Go To 6

6.

(Z1) HEATER GROUND CIRCUIT OPEN

Using a 12-volt test light connected to 12-volts, probe the (Z1) O2
Heater Ground circuit at the O2 Sensor harness connector.

Does the test light illuminate brightly?

Yes

>> Go To 7

No

>> Repair the open in the (Z1) O2 Sensor Heater ground cir-

cuit.

Perform the POWERTRAIN VERIFICATION TEST. (Refer
to 9 - ENGINE - STANDARD PROCEDURE)

7.

PCM

NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal
push out. Repair as necessary.
Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and
Ground circuits.

Were there any problems found?

Yes

>> Repair as necessary.

Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

No

>> Replace and program the Powertrain Control Module per Service Information.

Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

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ENGINE - ELECTRICAL DIAGNOSTICS - SRT-10

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