1998 Civic: code P0171: fuel pressure regulator?

Kaz Kylheku wrote in news: snipped-for-privacy@gmail.com:

250 miles versus 400.

You should reset the ECM /now/. That way you'll know for sure if any subsequent codes are set that are separate from the current P0171.

And if it's fixed, it's fixed; that's a good thing. But if you were smelling raw-gas out the tailpipe, I would have been expecting fuel-trim and/or misfire codes in addition to the lean code.

Reply to
Tegger
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it's a "P0" universal code which applies to all obdII vehicles tegger, not a honda-specific code like "P1", etc.

Reply to
jim beam

Yay! Went out by itself yesterday while driving: zero effort.

Bring laptop to car, plug in cables, fiddle with software: nonzero effort.

It's more satisfying if the MIL goes out by itself. The ECU diagnosed it, let it confirm the fix.

You never know; the threshold standard for confirming the fix may be stronger than the standard for merely not flagging a recurrence. Hysteresis is an obvious design choice for this kind of thing.

If alarms are programmed trigger and clear on the exactly the same threshold, then they will tend to flip-flop.

Suppose that, in a device, flomposity values greater than 19.7 trigger an alarm, and your fix reduces flomposity values to 19.2 percent. If you reset the alarm, it does not re-trigger. But suppose the management software requires a flomposity level of less than 10 percent in order to clear the alarm spontaneously. If you get it to do that, it's a better fix.

Reply to
Kaz Kylheku

I'm not sure that is the case, but your general idea is more or less correct. To set the codes in the first place requires the fault to occur in two consecutive driving cycles. To clear the code also requires 2 or

3 driving cycles without a fault. So having the light go out by itself is a stronger indication that it is working properly consistently even if the threshold for a fault is the same (which it probably is).

-jim

Reply to
jim

In article , "sjedgingN0Sp"@m@mwt,net says...

The big difference in clearing the code yourself vs letting the ECU do it is you immediately know that your fix worked, and you don't have the CEL shining at you for the cycles it takes to shut off. It is not my experience that it requires 2 consecutive driving cycles for the code to set. I have cleared codes and they reappear immediately upon restart. They probably get set according to the polling timing of the ECU. I don't see a reason for error codes to have ranged on/offs. You have an error when you hit a single point of measurement. If it is due to intermittent conditions it may turn off. Every o2 sensor error I've had, the code remained until the sensor was replaced. Just my experience. A home thermostat has a ranged on/off to reduce cycling, a safety valve has a ranged pop/reseat to reduce chattering. But for ODB an error is just an error in my experience, and if the CEL stays on something needs fixing or replacing. It never finds another point of measurement lower than required to set the code. But that's for a single code. Maybe some sensor errors cause other sensor errors to appear for good sensors. That may be classified as an intermittent code for the good sensor until the bad sensor is replaced. I do know that unplugging the TCC connector on some TH125 transmissions can cause the first and second gear sensors to throw their error codes, even though the trans is working fine without the lock-up. Those I usually call permanent intermittent codes.

Reply to
Bob Cooper

I can't find any specific explanation of it in this particular FSM ('99-'00 TL). The chart of DTCs has three numbers for each condition: a Pxxxx number, a different number that will flash on the MIL light if the SCS connector is shorted and occasionally a "temporary DTC" that has yet another Pxxxx number for some conditions. Its the "temporary DTC" column is sparse, but these two conditions (P0171 & P0172) are filled with P0170.

Reply to
E. Meyer

"E. Meyer" wrote in news:C853AA70.1D069% snipped-for-privacy@msn.com:

And right you are. It turns out the "temporary DTC" is set during the initial detection (first trip) for two-trip codes. If the same problem is detected on the second trip, a "mature" DTC is then set. In many cases, the temporary DTC is the same as the mature DTC, but P0171/172 are sometimes exceptions to that.

Only some models use P0170 as the temporary DTC for P0171/172. I have the Honda FSM for the OP's car, and it makes zero mention of any "temporary" DTCs. Its DTC list does not show a P0170. I have Honda docs for Civics

2000-and-up that do list temporary DTCs, but the temp. DTCs for P0171/172 are the same as the mature ones.

I'd have to buy another $10 subscription to Techinfo to be certain if P0170 is valid for the '98 Civic. But since the OP appears to have solved his issue by installing a new HO2S, it's not worth it.

Reply to
Tegger

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