New 02 sensor maybe wrong replacement

AQUARIAS JOHNSON

MEMBER
1998 ISUZU RODEO
3.2L
6 CYL
2WD
AUTOMATIC
188 MILES

This vehicle had been setting, I decided to use it, and took it for an inspection. There was not codes on it when parked or now, but the inspector said did you replace the battery on this vehicle? My reply was yes, I just installed a new one, he said I wont be able to inspect this vehicle as the codes are not set on it, you will have to drive it for 50 miles. Anyway I drove it for 60 miles and almost didn't get home the regulator went out. I replaced the Hitachi alternator and replaced the battery, now the ABS light is on, and the check engine light is on. I ran the codes and it came up with a p0154 so I purchased a new O2 sensor and replaced the bank 2 sensor 1 upstream, reset the codes with my Matco scanner and took it for a drive. I didn't get 5 miles and the check engine came on again, the same one, for the P0154. This is a really clean running little
V6 and there is no smoking and when I drive it around 50/60 and it is in close loop it starts lurching. The wires look as good as new, to the O2 sensors, it starts better than a new one, as it had the head replaced less than a 100 miles ago. Anyway I am wondering if the new 02 sensors I was shipped is the wrong one or what the part number SG454 4 wire heated sensor. It plugged in perfectly and screwed in perfectly. I don't know the manufacture of the 02. What is your opinion?

1 Reply

JACOBANDNICKOLAS

MECHANIC
109,867 POSTS

Welcome to 2CarPros.

First, replacing the battery is what caused the monitors to reset, so he was correct with that. Now, I don't know if this part was ordered, but honestly, it sounds like a bad sensor. If you cleared the code with a scanner and it came back, that indicated there is limited activity from the sensor and the vehicle will then return to what is called a closed loop operation for fuel determinations.

Here are things I need you to check. It seems you have a live data scanner.

1) Poor connection or damaged harness - Inspect the harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire-connection, and damaged harness.

2) Faulty HO2S heater or heater circuit - With the ignition "ON, " engine "OFF, " the HO2S 1 voltage displayed on the scan tool is normally 455-460 mV. A reading over 1000 mV indicates a signal line shorted to voltage. A reading under 5 mV indicates a signal line shorted to ground or signal lines shorted together. If not, disconnect the HO2S and connect a test light between the HO2S ignition feed and heater ground circuits. If the test light does not light for 2 seconds when the ignition is turned on, repair the open ignition feed or sensor ground circuit as necessary. If the test light lights and the HO2S signal and low circuits are OK, replace the HO2S.

3) Intermittent test - With the ignition "ON, " monitor the HO2S signal voltage while moving the wiring harness and related connectors. If the fault is induced, the HO2S signal voltage will change. This may help isolate the location of the malfunction.

Please let me know if this helps or if you have other questions. Honestly, I have a feeling you got a bad sensor, but step 2 will help you determine that.

Take care and I will watch for your response. Also note, if you didn't clear the code, it will take 40 warm up cycles for the code to clear itself. I also attached two pictures. They are flow charts for identifying the cause of this code.

Take care,
Joe

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