Long story, sorry. I was driving my 2000 Accord (200,000 mi) in torrential rain. The wipers slowed & went back on. The radio went on and off and then the engine cut out completely. It started later, with a jump. I opened the distributor cap and the fuse box in the engine compartment to chek if they were dry. They both were. At this point the check engine light went on and I brought it to my mechanic. He checked the diagnostic codes. He told me that the PCM itself had failed and other codes were coming up too, but were unreliable because of the PCM failure. He would not replace the PCM and told me to bring it to the dealer. The dealer said that the PCM did need to be replaced as well as the battery and the ELD. They said there were other codes coming up, but they were not reliable with a bad PCM. They wanted too much for the repair on an old car. I got a recommendation for a mechanic who does only Hondas and said he would replace the PCM with a used one (half the price of the dealer). I installed a new battery and then brought it to this mechanic. At this point the speedometer stopped working. He ran the diagnostics and said that it does NOT need a PCM. However, there are 4 sensors that are bad (including the ELD). He said that the O2 sensor showed that it was bad for 2 years. (dont understand this since the check engine light just came on and I had the catalytic converter replaced about 6 months ago). I don't understand how 4 sensors could all go at once. I'm wondering if this could all be from the battery/ELD problem. The car seems to run OK (but I've only driven it between mechanics). I don't know how to proceed. Any ideas?

. Test all under hood and under dash fuses with a test light or multimeter:

https://www.askmehelpdesk.com/cars-t...tml#post252145

Be very thorough, since it will save a lot of time and money.

. Check for codes yourself. Get a code reader and attach it to the data link connector under the dash. Report back with the specific codes.

. Test the alternator:

https://www.askmehelpdesk.com/cars-t...ml#post1973613

Many of your problems may be related to the alternator getting soaked. Report back with the regulated battery voltage.

If the PCM is bad, you can easily get a remanufactured one, with a lifetime warranty, and install it yourself. Let's see what you come up with, after performing the tests above. I'm skeptical that the PCM is bad, since the car runs fine. I suspect there was a problem with the alternator, when it got drenched. It may have affected the ELD system and the PCM. The question is if the damage was temporary or permanent. I would allow everything to dry out and then start your tests.

Floodings can short out alternators, sensors, and PCMs. My gut is that your situation is not too bad, since it runs.

Thank you so much for your help. (Based on what I could find out from the codes that were coming up - p1298, p1166 & p0141 first, then p1298 & p1167 at the dealer, then p0500, p1298, p1166, p1167, p0141 - I thought it might be the ELD and ordered a used fuse box, but have yet to receive it) It turned out that the #6 fuse on the driver side was blown. I replaced that. Then the check engine light would go on after about 10 minutes of driving. Also, after it warmed up, it was idling so low that it would stall. I brought it to autozone to check the code & the charging system. They said that the charging system is good. The code now is p1259. I tried to find out what I could about this code (could be a clogged filter on the soleniod valve. Taking the valve cover off is beyond me at this point) But I did try getting the engine up to 5000 rpms in first gear a few times, to try to clear it out. The check engine light came on again after about 10 minutes, however, it no longer stalls. Also, I checked the oil & it appears that it may have been over filled by about 1/2 quart. I also tried to check as much wiring as I could & don't see anything that looks bad. What do u think?

Start using full synthetic SAE 5W-30 engine oil (e.g. Mobil 1 or Pennzoil Platinum) right away. This is very important on VTEC engines. Engine pressure must reach a certain point in the VTEC solinoid, in order for the pin in each engine valve to be actuated for VTEC mode. A pin must mechanically slide to cause both intake valves per cylinder to operate as one. It's quite a system. Any sludge development can be a real problem. Synthetics will help safely clean the engine and ensure the solenoid works properly. Change the synthetic oil and filter every 6,000 miles or 6 months, whichever comes first. I would also use a premium filter, such as Mobil 1 EP or Purolator PureOne. This should take care of Code P1259. You will likely need to use a code reader to clear all codes and reset the ECM.

It's easy to increase the idle speed. Just loosen the inside jam nut on the throttle linkage and take up on the outside nut. Idle speed is likely around 700 rpm, when the engine is at normal operating temperature.

I don't think you should have to remove the valve cover, should the VTEC Solinoid have to be replaced. Frequently, they are located just behind the valve cover, on the passenger's side of the engine.

I have a similar issue and hope this resolves it, which seems to point to a bad wire from the Alternator based on the link included (I typed up what was in an image on that site, as all the codes mention is what I have my car showing, just have not had time to test it yet).

http://www.justanswer.com/honda/3tu5a-2000-accord-lx-getting-error-code-p1298-replaced.html

Alternator Short Can Cause DTC’s and Blown No. 6 Fuse

NOTE: This article applies to ’98 – 02 Accord L4s.

A short to the ground in the BLK/YEL alternator wire could cause the ECM/PCM to set certain DTCs and intermittently blow the No. 6 (15A) fuse in the driver’s under-dash fuse/relay box.

Which DTCs set depends on the whether the vehicle is a ULEV or not. Here’s the low-down:

ULEV Models

• DTC P0141 [secondary heated oxygen sensor (secondary HO2S) (sensor 2) heater circuit malfunction]
  
• DTC1166 (air fuel ratio (A/F) sensor (sensor 1) heater system malfunction]
  
• DTC P1298 [electrical load detector (ELD) circuit high voltage]
  
• A/T models only: A/T DTC P1798 (problem in the A/T clutch pressure control solenoid valve A circuit)

Non-ULEV Models

• DTC P0135 [primary heated oxygen sensor (primary HO2S) (sensor 1) heater circuit malfunction]
  
• DTC P0141 [secondary heated oxygen sensor (secondary HO2S) (sensor 2) heater circuit malfunction]
  
• DTC P1298 [electrical load detector (ELD) circuit high voltage]
  
• A/T models only: A/T DTC P0753 (problem in shift solenoid valve A circuit)
  
• A/T models only: A/T DTC P1753 (problem in torque converter clutch solenoid valve circuit)

To fix this problem, you need to repair the damaged wire insulation and replace the blown No. 6 fuse.