Toyota Engine Light Questions And Answers

Welcome to the Toyota engine light Question and Answer Page! This page should save you some time from submitting a duplicate question and having to wait for a response. We will include the model in most questions, so you can use the "Find on this page" function of your browser's "Edit" menu to get relevant info for whatever check engine light concerns you may have. For instance, just type in "Sienna" and search for responses relating to this vehicle. You could also type in a Toyota engine light code number by itself such as "P1130" and search all related responses for this trouble code. Just keep hitting "Find next" to go through all relevant check engine light responses. We don't recommend including a model year as this may make your search too narrow, and you may miss out on some relevant posts.

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Question:I have a 2000 Toyota Sienna and the Toyota engine light came on a couple of weeks ago. There was No perceivable difference in handling or fuel consumption. The Toyota dealer did not advise urgency, so I waited until after the holidays. Today, I got the OBD II codes scanned by a local shop and got codes P1130 and P1135. The vehicle has 37K miles and has been used gently. Should I replace the A/F Sensor 1 in Bank 1 Or should I take it to the dealer for further diagnosis? Is the Air/Fuel sensor on the front manifold? Thanks for your help.

Answer:Thanks for contacting us with your Toyota engine light question. Please refer to our article on Oxygen Sensor Diagnosis for some assistance with these codes. Both codes are for the the Air/Fuel sensor on bank 1, which is the bank towards the rear of the vehicle that includes cylinders 1, 3 and 5. The sensor is located in the exhaust pipe in front of the catalytic converter. The A/F sensor monitors the amount of oxygen in the gas and transmits this information to the computer so that it can adjust the fuel flow to maintain a correct air/fuel ratio (14.7:1). This sensor has a heater inside to bring it to temp. quickly, allowing for it to begin functioning sooner. Code P1135 is set when this heater output is more than 8 amps or less than .25 amps. Possible causes for this Toyota engine light code include the following. A/F sensor circuit is open or shorted. This could be a wiring concern or internal circuit concern which means the problem may exist in the A/F sensor itself or in the Electronic Control Module (ECM). Perform circuit tests as outlined in our Automotive Circuit Testing article to pinpoint the cause of this concern. You can check resistance across the sensor terminals with the sensor unplugged to determine if the heater is faulty. Measure across the pins with the Black/White and Black/Red wires on the sensor side, not the harness side. At 68F ambient temperature resistance should be .8 to 1.4 ohms. Toyota engine light code P1130 is set when the sensor voltage output remains the same with the engine running after it is at operating temperature. Possible causes for this code are the same as P1135, but also include a faulty fuel injector, air intake system leak or fuel pressure concern. From my experience, both of these codes are likely related. ECM failure is very uncommon, so I would suspect a wiring concern or internal A/F sensor problem. Check to be sure the connector is secure and plugged in correctly and then proceed with wiring tests. With an OBD II scan tool you can monitor the output voltage of the Air/Fuel sensor and it should switch from low to high values between 0 and 1 volt. I hope this information is helpful! Let me know if you need help with any future Toyota engine light concerns! Thanks, and enjoy the day!

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