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2001 Toyota Celica EMISSION CONTROL

Tiny
OMARTP795
  • MEMBER
  • 2001 TOYOTA CELICA
  • 4 CYL
  • FWD
  • AUTOMATIC
  • 136,000 MILES
How do you know that the O2 sensor is bad if you test it using a multimeter?
Monday, February 2nd, 2009 AT 5:54 PM

3 Replies

Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
HEATED OXYGEN SENSOR NO. 1 HEATER CIRCUIT
CAUTION:

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

NOTE:Heated oxygen sensor No. 1 refers to oxygen sensor closest to engine block. Heated oxygen sensor No. 2 refers to oxygen sensor farthest from engine block.

NOTE:For component location, see appropriate illustration in THEORY & OPERATION article.

Circuit Description
Heated oxygen sensor monitors exhaust gas oxygen content and delivers an input signal to ECM. ECM uses input signal to determine fuel injection system operation. DTC is set when heated oxygen sensor heater current draw exceeds 2 amps, or heated oxygen sensor heater current draw is.2 amp or less when heater operates. Possible causes are:
Heated oxygen sensor No. 1 heater circuit is open or shorted.
Defective heated oxygen sensor No. 1 heater.
Defective ECM.
Diagnostic Aids
Using scan tool, read freeze frame data. Freeze frame data records engine conditions when malfunction is detected.
Diagnosis & Repair
Access ECM in driver's side of engine compartment, next to battery. See Fig. 2. Turn ignition on. Using DVOM, backprobe ECM harness connector and measure voltage between ground and terminal No. 3 (Yellow/Red wire) at ECM harness connector E4. See Fig. 4. Voltage should be 9-14 volts. If voltage is as specified, replace ECM. If voltage is not as specified, go to next step.
Disconnect heated oxygen sensor No. 1 harness connector. Measure resistance between terminals B+ (Black/White wire) and HT (Yellow/Red wire) at heated oxygen sensor No. 1 (component side). See Fig. 6. Resistance should be 11-16 ohms at 68 °F (20 °C). If resistance is not as specified, replace heated oxygen sensor No. 1. If resistance is as specified, go to next step.
Repair wiring between ECM and heated oxygen sensor No. 1, and/or between heated oxygen sensor No. 1 and engine room junction box. See WIRING DIAGRAMS article.
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Monday, February 2nd, 2009 AT 6:13 PM
Tiny
GORDONIUS
  • MEMBER
  • 4 POSTS
Wow that is really complicated let me make this easier. Take a obd2 scanner and hook it to your car. With the car thoroughly warmed up(go drive it for 20 minutes or so) go to vehicle diagnostics, view data, your first o2 sensor should fluctuate between 0 and 1 volt(.040 to.800 or so) the back one should fluctuate much less (will respond to a little throttle)and be about.250 or so volts no voltage means bad 02 sensor, too high(over 1 volt) or always reading high instead of fluctuating are all signs of a bad 02 sensor
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Wednesday, December 9th, 2009 AT 6:21 PM
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
It is ain't it were professionals and were the worlds best, we get to the point and give all that is needed to help the helpless payed or not-Our style

He gots wire color code/s and specs
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Wednesday, December 9th, 2009 AT 6:30 PM

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