niccook

CAR SPECS: 1994 Honda LX Wagon. 2.2L MFI 4cyl, F22B2 engine. Automatic trans.

ORIGINAL PROBLEM: I got a "Check Engine" engine light on a trip during which the radiator fan went dead. Naturally, the engine ran hot (when not cooled from radiator circulation while on the road) until the fan was replaced. After replacing fan, the "Check Engine" light continued to display. An ECU check showed a Code 12 (EGR - exhaust gas recirculation lift valve). In response, I tried 3 different fixes, each after the prior one did not solve the problem:

Fix 1: Cleaned EGR ports, grooves, and EGR valve. Replaced EGR valve and chamber gaskets.
Fix 2: Replaced EGR valve unit (new one). [BWD/Intermotor EGR Valve Part No. EGR1340 from Advance Auto Parts].
Fix 3: Replaced Vacuum Solenoid. [Duralast EGR Vacuum Solenoid Part No. EVS155 from Autozone].

RESULT AND CONTINUING PROBLEM: After doing fixes 1, 2, and 3, I still get a "Check Engine" leading to a Code 12 after the car heats up and reaches operating temperature. HOWEVER, after the car has warmed to full operating temperature and a "Check Engine" is showing, if I then turn off and then restart the car, the "Check Engine" will not come on again.

[For instance, I have taken the car on a 6 hour trip. After initial warm-up, the "Check Engine" light displayed, the car was turned off and then restarted. After that, the check engine light did not again come on for the whole rest of the trip, even though the car was turned off/on during several pitstops that weren't long enough for the engine to cool down much.]


Q1: What causes the "Check Engine" light after a cold start, but not again after I have restarted when the car? Could this behavior have to do with a bad temperature sensor or with some kind of bad info going to the EGR sensor or ECU? What should I do next to check/replace to deal with this problem?

Note: I suspect the EGR works OK and that the "Check Engine" light is showing a false positive derived from erroneous temperature info to the ECU, given that the Check Engine/Code 12 does not generate after a second restart after the car has warmed up. I wonder if this has anything to do with the fact that the problem began while the engine was running hot due to the dead radiator fan (see above). I speculate that some sort of bad temperature info is triggering the ECU to display the "Check Engine" light/Code 12 after cold start, but not after a restart once the car has warmed up. Are any such causal links possible?

Q2: Will the continuing Code 12 block any further ECU codes from showing, or will the ECU flash Code 12 and then any additional codes?

Thanks all for any input, Nic

GhostAccord

I'll have to look into the code 12 a bit more. As for your second question. If there are other codes they will not be blocked. They will be stored in the memory and flash along with the code 12.

Just out of curiosity, have you checked the vacuum hoses to the EGR valve? Even though this seems like it might be a problem with a sensor more than a valve issue. Could be an O2 sensor or an ECU thing!

niccook

>>Just out of curiosity, have you checked the vacuum hoses to the EGR valve? Seems like this might be a [temperature?] issue more than a valve issue. Could be an O2 sensor or an ECU thing!

A: I have not checked vacuum except to see that the hoses look good and are tightly connected. Ain't yet invested in a vacuum gauge, and the repair manual vac check tree (not to mention electrical) is a little complicated for my skill set--and since vacuum leaks are so often elusive, I'm not confident of my possible diagnosis. I love to research, learn/try fixes (just to know + save a buck) but my skill level is usually basic diagnosis + remove/replace. But learning/practice makes perfect (or at least better), and I hate throwing parts at a problem. Will research O2 sensor possibilities. ECU, maybe but I sure hope not... ca$h cow, although Ebay is always there. Thanks for the reply

phootbag

You need to hook a vacuum guage to the line going to the EGR valve. Gently and slowly tip into the throttle ( in park ) and watch the guage. As you slowly increase RPM, the vacuum to the EGR valve should increase. I've seen problems with the vacuum control valves on the driver side of the engine bay.

Steve Z

I would try clearing the codes by disconnecting your battery for a minute. See if that helps.

niccook

Thanks for the tips. I guess I'll go the vacuum guage route next over the wkend. I have cleared the ECU several times, but'll also do that again.

lowgroove

any luck with this yet im in the same boat

niccook

Sorry. I am just driving with it for the time being, as the car works fine, and am not in a position to devote time to it. Will post again when I can get to it and have any results to report. Could be a while. I'll be interested in anything you may discover of course.

holmesnmanny

Did you clean out the port on the cylinder head side ? Did you put a new vacuum hose on ?

Secondly, I can't imagine that code coming on when the car is cold since the egr doesn't operate until the car has warmed up to operating temperature. This assumes that you cleared the code after turning off the car the night before.

This could suggest the ecu is bad. You should try swapping in another ecu if the above two ideas were done.

lowgroove

where can you get that vacuum hose at

holmesnmanny

They sell bulk vacuum hose at most auto parts stores. Just take it off and have them match it up. They usually have them on wheels in the back of the store.