Mechanics

CODE P0132 AND P0138 O2 SENSOR PROBLEM

1999 Jeep Grand Cherokee • 6 cylinder 4WD Automatic • 161,000 miles

I am receiving p0132 and p0138 OBD2 codes on my vehicle. While investigating I found that the O2 sensor relays on the distribution box are missing, further more I found that the relay compartment is not having any terminals to hold and connect the relay in the distribution box, located under the hood above the right wheel just beside the battery. I have new O2 sensors but before installing I want to make sure; if I need those relays in place or are they located some where else. Would the O2 sensors work without those relays?
Avatar
Wudaal
August 10, 2011.



If your vehicle is not of California specifications, you do not need them.

Non California specifications do not use any relays.

KHLow2008
Aug 10, 2011.
I would make sure the o2 are bad first. Did you check the fuses for the heaters? The code never identifies a bad part just a failed system. That why you need a real diag from a real tech to verify before spending money you did not have to spend.

Roy

ASEMaster6371
Aug 10, 2011.
Actually I dont know, but because there are no wires for relays in distribution box, so I think it is not of California specifications, if this is the situation then how shall I proceed with the troubleshooting?

Tiny
Wudaal
Aug 11, 2011.
I got one another problem. The cooling fan wires gets extremely super hot. Can you help please?

Tiny
Wudaal
Aug 11, 2011.
DTC P0132: 1/1 O2 SEN SHORTED TO VOLTAGE

NOTE: DTC P0132: 1/1 O2 SEN SHORTED TO VOLTAGE is monitored with engine running for more than 4 minutes and engine coolant temperature reaches 180°F (82.2°C). DTC may be stored in Powertrain Control Module (PCM) when PCM senses that 1/1 Heated Oxygen Sensor (HO2S) voltage is more than 1.5 volts. Possible causes are: defective 1/1 HO2S, defective PCM, defective connectors or defective wiring.

NOTE: 1/1 HO2S is located in upstream position.

1. Using scan tool, read DTCs. If DTC SPECIFIC GOOD TRIP COUNTER is
displayed and displayed count is "0", go to next step. If DTC SPECIFIC GOOD TRIP COUNTER is not displayed or displayed count is not "0", go to step 11).

2. Turn ignition on, with engine off. Using scan tool, actuate O2 HEATER TEST, then monitor 1/1 HO2S voltage. If voltage drops below 1.5 volts within 2-3 minutes during O2 HEATER TEST, go to next step. If voltage does not drop below 1.5 volts within 2-3 minutes, go to step 4).

3. Turn ignition off. Disconnect 1/1 HO2S connector. Start engine and allow it to idle. Using a voltmeter, check voltage on 1/1 HO2S connector, signal circuit (Light Green/Red wire). If voltage is 5.5 volts or less, go to step 11). If voltage is more than 5.5 volts, repair signal circuit for short to voltage. Perform TEST VER-5A.

4. Turn engine off. Ensure 1/1 HO2S connector is still disconnected. Turn ignition on, with engine off. Using scan tool, monitor 1/1 HO2S voltage while connecting a jumper wire between 1/1 HO2S connector, signal circuit (Light Green/Red wire) and sensor ground circuit (Black/Light Blue wire). If voltage does not change from 5 volts to less than one volt, go to next step. If voltage changes from 5 volts to less than one volt, go to step 8).

5. Ensure ignition is off. Ensure 1/1 HO2S connector is still disconnected. Using an ohmmeter, check resistance between ground and 1/1 HO2S connector, sensor ground circuit (Black/Light Blue wire). If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair open sensor ground circuit. Perform TEST VER-5A.

6. Turn ignition off. Ensure 1/1 HO2S connector is still disconnected. Disconnect PCM connectors. PCM is located in engine compartment. Clean and/or repair connectors as necessary. Using ohmmeter, check resistance of 1/1 HO2S signal circuit (Light Green/Red wire) between 1/1 HO2S connector and PCM connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair open signal circuit. Perform TEST VER-5A.

7. At this time, PCM is assumed to be defective. Replace PCM. Perform TEST VER-5A.

8. Turn ignition off. Ensure 1/1 HO2S connector is still disconnected. Turn ignition on, with engine off. Using scan tool, actuate O2 HEATER TEST. Using a voltmeter, on vehicles with California emissions, check voltage on 1/1 HO2S connector, heater relay output circuit (Violet/White wire). On vehicles with Federal emissions, check voltage on 1/2 HO2S connector, ASD relay output circuit (Orange/Dark Green wire). On all vehicles, if voltage is more than 11 volts, go to next step. If voltage is 11 volts or less, repair open heater relay output circuit or ASD relay output circuit. Perform TEST VER-5A.

9. Turn ignition off. Ensure 1/1 HO2S connector is still disconnected. Using an ohmmeter, check resistance between ground and 1/1 HO2S connector, heater ground circuit (Black wire). If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair open heater ground circuit. Perform TEST VER-5A.

10. At this time, 1/1 HO2S is assumed to be defective. Replace 1/1 HO2S. Perform TEST VER-5A.

11. Turn ignition off. Visually inspect related connectors and wiring harness for damage. Repair connectors and wiring harness as necessary. Perform TEST VER-5A. If connectors and wiring harness are okay, test is complete.

DTC P0138: 1/2 O2 SEN SHORTED TO VOLTAGE

NOTE: DTC P0138: 1/2 O2 SEN SHORTED TO VOLTAGE is monitored with engine running for more than 4 minutes and engine coolant temperature reaches 180°F (82.2°C). DTC may be stored in Powertrain Control Module (PCM) when PCM senses that 1/2 Heated Oxygen Sensor (HO2S) voltage is more than 1.5 volts. Possible causes are: defective 1/2 HO2S, defective PCM, defective connectors or defective wiring.

NOTE: 1/2 HO2S is located in downstream position.

1. Using scan tool, read DTCs. If DTC SPECIFIC GOOD TRIP COUNTER is
displayed and displayed count is "0", go to next step. If DTC SPECIFIC GOOD TRIP COUNTER is not displayed or displayed count is not "0", go to step 11).

2. Turn ignition on, with engine off. Using scan tool, actuate O2 HEATER TEST, then monitor 1/2 HO2S voltage. If voltage drops below 1.5 volts within 2-3 minutes during O2 HEATER TEST, go to next step. If voltage does not drop below 1.5 volts within 2-3 minutes, go to step 4).

3. Turn ignition off. Disconnect 1/2 HO2S connector. Clean and/or repair connector as necessary. Start engine and allow it to idle. Using a voltmeter, check voltage on 1/2 HO2S connector, signal circuit (Black/Dark Green wire). If voltage is 5.5 volts or less, go to step 11). If voltage is more than 5.5 volts, repair signal circuit for short to voltage. Perform TEST VER-5A.

4. Turn engine off. Ensure 1/2 HO2S connector is still disconnected. Turn ignition on, with engine off. Using scan tool, monitor 1/2 HO2S voltage while connecting a jumper wire between 1/2 HO2S connector, signal circuit (Black/Dark Green wire) and sensor ground circuit (Black/Light Blue wire). If voltage does not change from 5 volts to less than one volt, go to next step. If voltage changes from 5 volts to less than one volt, go to step 8).

5. Ensure ignition is off. Ensure 1/2 HO2S connector is still disconnected. Using an ohmmeter, check resistance between ground and 1/2 HO2S connector, sensor ground circuit (Black/Light Blue wire). If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair open 1/2 HO2S sensor ground circuit. Perform TEST VER-5A.

6. Turn ignition off. Ensure 1/2 HO2S connector is still disconnected. Disconnect PCM connectors. PCM is located in engine compartment. Clean and/or repair connectors as necessary. Using ohmmeter, check resistance of 1/2 HO2S signal circuit (Black/Dark Green wire) between 1/2 HO2S connector and PCM connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair open signal circuit. Perform TEST VER-5A.

7. At this time, PCM is assumed to be defective. Replace PCM. Perform TEST VER-5A.

8. Turn ignition off. Ensure 1/2 HO2S connector is still disconnected. Turn ignition on, with engine off. Using scan tool, actuate O2 HEATER TEST. Using a voltmeter, on vehicles with California emissions, check voltage on 1/2 HO2S connector, heater relay output circuit (Violet/Orange wire). On vehicles with Federal emissions, check voltage on 1/2 HO2S connector, ASD relay output circuit (Orange/Dark Green wire). On all vehicles, if voltage is more than 11 volts, go to next step. If voltage is 11 volts or less, repair open heater relay output circuit or ASD relay output circuit. Perform TEST VER-5A.

9. Turn ignition off. Ensure 1/2 HO2S connector is still disconnected. Using an ohmmeter, check resistance between ground and 1/2 HO2S connector, heater ground circuit (Black wire). If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair open heater ground circuit. Perform TEST VER-5A.

10. At this time, 1/2 HO2S is assumed to be defective. Replace 1/2 HO2S. Perform TEST VER-5A.

11. Turn ignition off. Visually inspect related connectors and wiring harness for damage. Repair connectors and wiring harness as necessary. Perform TEST VER-5A. If connectors and wiring harness are okay, test is complete.

TEST VER-5A

Final Procedure

1. Inspect vehicle to ensure all engine components are connected. Reassemble and reconnect components as necessary. If any DTCs have not been diagnosed, return to appropriate test(s) listed under SELF-DIAGNOSTIC TESTS. See DTC MESSAGES & CODES table and finish diagnosing remaining DTCs as necessary. If all DTCs have been diagnosed and repaired, go to next step.

2. Connect scan tool to Data Link Connector (DLC) if not previously done. Ensure fuel tank is at least 1/4 full. Ensure A/C is off. Go to next step.

3. Proper way to ensure DTC is repaired is to allow Powertrain Control Module (PCM) to run monitor. Monitor operation may be observed on scan tool. All specified enabling conditions for specified DTC must be met before PCM will operate monitor. Go to next step.

4. Using scan tool, monitor pretest enabling conditions until all conditions have been met. Once all enabling conditions are met, observe appropriate monitor for DTC on scan tool. If repaired DTC has reset or is Seen in monitor while on road test, repair is not complete. Check for related Technical Service Bulletins (TSBs)
and return to appropriate test listed under SELF-DIAGNOSTIC TESTS. See DTC MESSAGES & CODES table. If no DTCs return, test is complete. Go to
step 6).

5. If another DTC exists, return to appropriate test(s) listed under SELF-DIAGNOSTIC TESTS. If no DTCs return, test is complete. Go to next step.

6. Turn ignition on, with engine off. Using scan tool, erase DTCs. Turn ignition off. Disconnect scan tool. Test is complete.

As to the hot fan wires, the motor could be failing increasing the resistant and allowing heat to build up. Check the grounding circuit for the fan motor and ensure they are secure.

KHLow2008
Aug 11, 2011.
WoW, thats well explained. But unfortunately I dont have a professional scan tool, can I do all this with ordinary scan tool which only show stored DTC?
Shall I ask a separate question regarding the hot wires as I need some more details to tackle the problem. It is really more annoying that the O2 sensors.

Tiny
Wudaal
Aug 12, 2011.
A code reader would not show you the specific data for the test. Instead, you can skip those that involves the scan tool and perform measurements on the resistances and wiring continuity.

As to the hot wires, it is ok, you can continue here. You can also ask a separate question so that more technicians can get involved.

If the wire is hot near connectors, check the connectors for secureness. Ensure the connector terminals are tight. Any looseness would increase the resistance and allow heat to build up.

If the whole length of wire is hot, either the wire is below capacity or the fan is going bad resulting in increased resistance to the wires.

KHLow2008
Aug 12, 2011.
There are two wires running to the fan. Earlier there was a latch connecting them to the fan. One of these wires got extremely hot and it burnt the latch. Then I connected them directly again, and again that wire is getting super hot, to the extent that will cut off by itself.

Tiny
Wudaal
Aug 13, 2011.
The wires could be bad due to overheating. Try replacing them with higher capacity wires and retest. DO NOT increase the fuse amperage.

KHLow2008
Aug 13, 2011.