Header = low voltage light

[09SuperWhite]

I have done tons of searching and even called the company i bought my Tsudo 4-2-1 header and s-pipe from to answer my and question and so far no one has been able to fix my issue! My problem is aftering installing my headers and s-pipe i put on the CEL Elim. onto the s-pipe which was including with my headers so i would not have the annoying CEL. Once eveything was done i start the car and the check engine light comes on with a code saying Bank1 Sensor 1 o2 sensor low voltage! The company i got my header from says this is a new issue to them that CEL Elim. should make the CEL go off and they don't know what to tell me lol! The car runs great i just don't like seeing that light everyday. So any help would be great. Thanks

[navylife59]

Let me clarify something first, what is the exact DTC (CEL code)? It is important to know what it is. There are 2 Oxygen sensors, 1. The A/FR wideband (Bank1Sensor1) and the HO2 (Heated Oxygen) narrowband (Bank1Sensor2). Sensor1 is expensive and the most important (car should run bad) and Sensor1 is not so expensive and not so important (car will run fine without it). Being that you are frustrated with this issue and I don't know when I can get back on here, I will take the assumption that you problem is with Sensor2 (s-pipe). Sensor1 (header) could have same issues and resultant fixes, but if the sensor was damaged, the car would run erradict.

You are experiencing a common problem. First, take a look at this article to get an understanding of what is going on.
http://www.club-tc.com/forums/engine...event-mil.html

You are more than likely having this issue do to an air leak either around the metal crush gasket on the sensor or the donut at the header/s-pipe joint. The s-pipe/mid-pipe joint may either be a donut or flat crush gasket depending on the Tsudo's design. Replacing these gaskets and torquing properly might resolve this issue. Unfortunately, I have not found a local source for replacement metal crush gaskets for the O2 sensor. Even the Dealership cannot get them. The sensors come from Denso with them so if you can speak Japanese, I can get you a phone number. For Sensor1 issue, all apply with the inclusion of the header gasket.

This might win you the Darwin Award, but did you make sure to plug the sensor back into the car harness? Don't laugh, I did! Was in a rush to get my car off the rack before the Auto Hobby on Base closed and plumb forgot to check my work area. The car will run fine without it, just not efficient.

There is also the possibility that you may have broken a wire in the sensor's dongle if it got all twisted up when it was removed or installed. As I stated in the article, you should use anti-seize to make sure the threads are sealed but be very careful not to get it on the sensor element barrel or on the outside above the flats (nut portion). There are little air vents that look like white or light grey dots around the circumference. This allows the sensor to sample the outside air for voltage differential comparison with O2 content in the exhaust gas stream. If they are clogged, it will read inaccurately. The ECM knows roughly where the sensor should be reading based on inputs from other sensors. It periodically performs checks and will trip a DTC if it is not within the expected parameters. The ECM also performs checks on the integrity of the sensor and will trip a DTC if not within established guidelines.

[navylife59]

The Toyota Service Manual states the following for possible causes:

Bank1Sensor1
1. Open in Air-Fuel Ratio (A/F) sensor heater circuit
2. A/F sensor heater
3. EFI relay
4. ECM

Bank1Sensor2
1. Open in Heated Oxygen (HO2) sensor heater circuit
2. HO2 sensor heater
3. EFI relay
4. ECM

Follow this linked article for how to use a multimeter to check your sensors.
http://www.club-tc.com/forums/engine...html#post35713

More of an FYI Knowledgebase Article, it reaffirms my points.
http://www.club-tc.com/forums/tc-kno...nsors-mil.html