So, I just purchased a Civic. I've also previously owned a 1987 CRX HF, and a 1980 Civic 1500DX with the Hondamatic.

Onward into the world of OBDII.

The previous owner's going to replace the gas cap, as he's concluded that the CEL is on for that reason. However, a few minutes ago, I plugged in my scanner, and came up with three total codes.

I figured that, instead of just starting to replace things without entirely knowing what I was doing, I'd see if any of them are related somehow, or causing some kind of cascading effect.


So, they are:

• P0108 - MAP/BARO circuit high input
• P0122 - TPS / Pedal Position Sensor A Circuit Low Input
• P1475 (correction, P1457, I'm a typing klutz) - Mfg Control Aux Emission Control

I've stumbled across another thread that seems to indicate that the MAP Sensor and TPS plugs are the same, and it's possible a previous owner or shop could have mixed them up. I've also read that replacing the gas cap is the first step for P1475.

But, do the three of these together mean anything? If not, then does the combination of the first two suggest any particular issue that wouldn't be the case if only one or the other were present?

As it stands now, it feels like it's running as it should, but I've only put about 25 miles on it since purchasing it, so my view on what it *should* feel like might be off.

Thanks in advance!

 

Be wary.

If you reset the ECU, do all codes return?

The first two codes are definitely not caused by a bad gas cap, and the third code is likely a typo (P1456 or P1457?). Double check it.

Has the car been modified, for example an engine swap? The stock engine should be a D16Y7 and the ECU should be a P2E.

https://honda-tech.com/honda-civic-d.../#post48684945

 

Yes, you're right, it's P1457 - I fumble-fingered when I typed up my message.

The car is 100% bone stock to the best of my knowledge. The owners I got it from didn't seem like the tuner/modder type, though I can't say for anyone who owned it before they did.

I doubt the ECU has been changed... is the ECU easily accessible?

EDIT: ok found a thread where accessing it is discussed . . ugh, definitely don't want to pull up the rug - doesn't look like the interior's ever been molested.

 

High output and low input circuits means that there could be a wiring issue.

 

My guess would be that the first two codes don't return. Not sure about the last one.

Behind passenger kick panel

 

Update: Turns out that he had a new TPS, not a new fuel cap, and we installed it yesterday, and have the correct 0.5v at idle, but his multimeter read 4.7v wide open rather than 4.5v as was stated on the sheet.

We figured adjusting the position to lower the max would also lower the idle, so we let it be.

Cleared the codes, and I drove for about 20 miles total. So far, no CEL, though I don't know how long it takes until it would pop back up again.

 

^The voltage is perfectly normal.

But was there anything wrong with the original TPS?

 

Visually, no. We didn't backprobe the voltages with the old one. Still, I kept the old one, just in case.

Will keep things posted as the workweek starts. Definitely an interesting feeling driving something for the first time in over a decade that didn't qualify as a "land yacht"

 

Well, I think I'm in the clear - I've put 300 miles on the car since the TPS was changed and I cleared out the codes, and so far, the CEL has not come back on.

I've been doing about 75-80% highway driving, and, on my first fill-up, I've gotten 35.9 MPG. I guess things are working as they should.

 

Alrighty, dredging this one up from the past...

After 1000 miles, the P1457 came back. Kept driving, and my (mostly highway) MPG ranges between 35 and 39 MPG (one tank was 33.5 but that was with constant AC use)

Kept driving like that, hoping maybe it would go away. But, after 3000 more miles, I reset it. It came back within 600 miles this time.

Today I checked. It's an Actron CP9145 that I'm using.

• P0122 mod$10 - TPS / Pedal Position Sensor A Circuit Low Input
• P1457 mod$10 - Mfg Control Aux Emission Control
• P1457(pending) mod$10 - Mfg Control Aux Emission Control

So, no issues with the MAP/BARO sensor anymore.

BUT, does the mod$10 mean anything specific? I can't recall if that was there the first time. It was an oversight on my part not to put it if it was there back then.
Also, since I know the TPS was replaced at the end of March, I can't figure why the issue has come back after a few thousand miles.

And, the P1457 showing up twice. The pending notation according to Actron's manual means:
Ok, so I completely understand what that means. What I don't understand is why P1457 is showing up twice, once normally, and once as a pending code. Any thoughts on why?

Also, if backprobing the TPS gives me the expected voltages, what would my next course of action with regard to that be?

 

You need to do the service manual troubleshooting for both codes.

For example, why would you assume that P0122 could only be caused by a bad TPS?

 

Check the TPS wiring to ensure its not damaged. Do the VIN's on the engine match the car?

 

Google: 17310S84A02

PM @deschlong for more info.