1996 Toyota Camry Check Engine Light

  • 6 CYL
  • FWD
  • 219,500 MILES

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Asked on February 15, 2011

1996 Toyota Camry XLE with 219 miles
6 cyl 3.0 Manual Front Wheel Drive

1996 Toyota Camry

I am working on a 1996 Toyota Camry with a 3.0L V6 (1MZ-FE). After the Check Engine Light came on and there was a noticeable difference in the way the vehicle runs, especially on start up, I pulled the codes to find PO 302 306 171 100 and 110 stored. I began troubleshooting by replacing the spark plugs, clearing the codes and test driving the vehicle. There was a noticeable difference in the way the vehicle ran, however, the Check Engine Light tripped again. I pulled the codes again and came up with PO 171. I ended up installing a used MAF sensor I had on hand, cleared the code, test drove the vehicle and again had the Check Engine Light come on. I pulled the codes again and came up with PO 171, system to lean bank 1. I am not sure what the next step in the diagnosis process would be? Any help would be greatly appreciated. On a side note I noticed a small amount of oil in the intake hose between the MAF sensor and throttle body. Any ideas? Thank you in advance.

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have the same problem?
Wednesday, February 16th, 2011 AT 7:24 PM

1 Reply

  • 42,008 POSTS

Hi eric gauch,

Thank you for the donation.

Here are the diagnostic procedures.


CAUTION: If ECM replacement is instructed in following testing, always ensure ECM connectors and ground circuit are okay. If either are suspect, repair and repeat testing to confirm ECM malfunction.

Circuit Description
Fuel trim refers to feedback compensation value compared against basic injection time. Fuel trim includes short-term and long-term fuel trim.

DTC P0171 is set when fuel trim is rich beyond a certain value. Possible causes are:

Air intake hose loose.
Fuel line pressure.
Injector blockage.
Heated oxygen sensor.
Mass Airflow (MAF) sensor.
Engine Coolant Temperature (ECT) sensor.

DTC P0172 is set when fuel trim is lean beyond a certain value. Possible causes are:
Fuel line pressure.
Injector blockage or leak.
Heated oxygen sensor.
Mass Airflow (MAF) sensor.
Engine Coolant Temperature (ECT) sensor.

NOTE: Oxygen sensor located nearest radiator is referred to as left side sensor.

Diagnosis & Repair

1. Inspect all air induction components. Repair as necessary. If air induction components are okay, connect scan tool. Start engine and warm to normal operating temperature. Monitor heated oxygen sensor output voltage and short-term fuel trim.

2. If scan tester indicates a lean condition (.55 volt or less, +20 trim) or rich condition (.4 volt or more, -20 trim), go to next step. If results are other than shown, see DTC P0130 - HEATED OXYGEN SENSOR CIRCUIT (RIGHT SIDE, NO. 1), DTC P0150 - HEATED OXYGEN SENSOR CIRCUIT (LEFT SIDE) circuit test.

3. Inspect fuel pressure. Repair as necessary. If fuel pressure is okay, inspect fuel injectors. Replace injectors as necessary.

4. If all injectors are okay, inspect Mass Airflow (MAF) sensor and Engine Coolant Temperature (ECT) sensor. Replace as necessary. If both components are okay, inspect ignition system. Repair as necessary. If ignition system is okay, replace ECM and retest.

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Wednesday, February 16th, 2011 AT 7:36 PM

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