2000 Honda Civic P0122

CMEAND1

MEMBER
2000 HONDA CIVIC
4 CYL
FWD
MANUAL
98,000 MILES

Hey car pros I have a code p0122 for my car. That is tps sensor/pedal input low. I took my car to performance shops and have been working on it lately. We measures the tps and was at the right volts when open and closed. We also check the wiring for the tps plug to make sure there are no damage or breaks. We reset it couple times and the cel comes back on with the same p0122 code. We have no other option left but perhaps replace the ECU. But I dont know if there is a way to test the ECU, but my ecu has been reset many times and had tons of cel that has been reseted in all kind of ways with the scanner, pulled out the fuels, and manually reset the ecu by pulling it out and plugging it back in. There are also rare symtoms of little/no accelration and wierd idles and surges. It seems to be an intermit problem so we dont know what to do as for now. Any suggestions? Thank you

5 Replies

KHLOW2008

MECHANIC
41,815 POSTS

Hi CmeAnd1,

You can test the ECM for power supply etc.

Is your engine D16Y5?

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Wednesday, December 31st, 2008 AT 1:58 PM

CMEAND1

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8 POSTS

My engine is a b16a2 DOCH VTEC

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Wednesday, December 31st, 2008 AT 3:35 PM

KHLOW2008

MECHANIC
41,815 POSTS

Ok,

I got the testing procedures for this code, hope it is helpful.

DTC P0122: THROTTLE POSITION (TP) SENSOR LOW VOLTAGE INPUT

1. Start engine and run at 3000 RPM with no loads and transmission in Park or Neutral until radiator fan comes on. Turn ignition off. Turn ignition on. Using scan tool, check throttle position. If reading is about 10 percent (.49 volt) with throttle fully closed and 90 percent (4.5 volts) with throttle fully opened, problem is intermittent. System is okay at this time. Check for poor connections or loose wires at TP sensor and PCM connectors. See appropriate wiring diagram in WIRING DIAGRAMS article. If reading is not as specified, go to next step.

2. Turn ignition off. Disconnect TP sensor 3-pin connector. Turn ignition on. Measure voltage between TP sensor harness connector terminals No. 1 (Green/Black wire) and No. 3 (Yellow/Blue wire). See Fig. 6 . If about 5.0 volts does not exist, go to next step. If about 5.0 volts exists, go to step 4 .

3. Using backprobe set, measure voltage between PCM 31-pin connector "C" terminals No. 18 (Green/Black wire) and No. 28 (Yellow/Blue wire). See Fig. 3 . If about 5.0 volts exists, check for open in Yellow/Blue wire between PCM 31-pin connector "C" and TP sensor. If about 5.0 volts does not exist, substitute a known-good PCM and recheck. If symptom or indication goes away, replace original PCM.

4. Turn ignition off. Measure resistance between TP sensor connector terminals No. 1 and 2 with throttle fully closed. See Fig. 6 . If resistance is about 500-900 ohms, go to next step. If resistance is not as specified, replace throttle body (TP sensor cannot be serviced separately).

5. Measure resistance between TP sensor connector terminals No. 2 and 3 with throttle fully closed. See Fig. 6 . If resistance is about 4500 ohms, go to next step. If resistance is not as specified, replace throttle body (TP sensor cannot be serviced separately).

6. Reconnect TP sensor 3-pin connector. Turn ignition on. Using backprobe set, measure voltage between PCM 31-pin connector "C" terminals No. 18 (Green/Black wire) and No. 27 (Red/Black wire). See Fig. 3 . If voltage is about 0.5 volt with throttle fully closed and 4.5 volts with throttle fully open, substitute a known-good PCM and recheck. If symptom or indication goes away, replace original PCM. If voltage is not about 0.5 volt with throttle fully closed and 4.5 volts with throttle fully open, check for short in Green/Black wire between PCM connector and TP sensor.

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Thursday, January 1st, 2009 AT 6:23 AM

CMEAND1

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Okay thx for the advice, I will bring this to my performance shop and have them read it.

Also another code I've been having for couple months is the code p0420 which means catilac effiecntly below threshold (bank 1). Everytime this code comes on I reset it and it doesnt come on often. Perhaps about once a month, however as time passes by it reoccurs more often. I also replaced my front o2 sensor bank1 coouple mnoths back, but did not replace the 2nd o2 sensor yet. I have been told that my cat is going bad but I am not sure if replacing the 2nd O2 sensor will prevent the code p0420 to come on again. Or perhaps are there ways to test out the sensors?

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Thursday, January 1st, 2009 AT 6:43 AM

KHLOW2008

MECHANIC
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Hi CmeAnd1,

DTC P0420: CATALYTIC SYSTEM EFFICIENCY BELOW THRESHOLD

NOTE: If DTCs P0137, P0138, and/or P0141 are indicated, trouble shoot DTC P0420 last.

NOTE: DTC P0420 is set and MIL illuminated when malfunction has been detected during 2 consecutive trips.

Perform PCM reset procedure. Start engine and run at 3000 RPM with no loads and transmission in Park or Neutral until radiator fan comes on. Allow engine to idle. Connect SCS service connector. Test drive vehicle at 40-55 MPH for about 2 minutes. Decelerate for at least 3 seconds with throttle fully closed. Reduce vehicle speed to 35 MPH, and hold it there until readiness code comes on. If DTC P0420 is not indicated, problem is intermittent. System is okay at this time. If DTC P0420 is indicated, inspect Three-Way Catalytic Converter (TWC) for plugging, melting, cracking and exhaust system leaks. Replace as necessary.