oldskewel

iTrader: (1)

'91 LS400 with 188k miles. 2nd owner, PO is my father in law. Dealer seviced by him, self-serviced by me since 1997.

I've been getting the CEL coming and going for a little while now. Checked codes over the weekend and found an Engine Code 25 = Air-fuel ratio lean malfunction.

O2 sensors are still original at 188k miles. Car runs great otherwise. I pulled the diagnostic cover in the engine bay and monitored O2 sensor voltages, and they seem OK (I wish they didn't). I have the service manual, and looking through all the troubleshooting steps, it does not look easy. E.g., check fuel pressure is about one of a hundred things I'll need to be checking.

So I'm thinking to replace the O2 sensors now, even though the voltages are good. Does that make sense? Also, I'd go with OE brand, but universal if I can get them. Right?

Second (or first?), I've been aware of the ECU capacitors issue for a while. The only other possible symptom is that sometimes the transmission seems to be in a lower gear than it should be (e.g., when coasting, there feels like too much drag).

I believe EGR pipe problems could cause this code as well - right? The last time my father in law had it dealer serviced, they said the EGR pipe was cracked and he'd need a new one. I went and bought one, but after learning how hard it is to install, help off on doing that, and until now have had no EGR pipe issues at all (and this might not be it). There is no exhaust sound or anything like that.

Comments?

Thanks.