P0125 ECU Code issue WARNING
05-09-19, 07:20 PM
#1
Driver School Candidate
Thread Starter
P0125 ECU Code issue WARNING
Because I did some searches for this Code and saw that this code seems to be troublesome and sometimes hard to trouble shoot I thought id share this recent experience from the 1997 ES 300
I was getting P0135, O-2 Bank 1 Sensor 1 Heater circuit and P0330 Knock sensor 2 ECU Codes
I replaced the Bank 1 Sensor 1 O-2 sensor. After doing this I cleared the the Codes and the 0135 code went away,
Immediately I got the P0125, Insufficient Coolant Temperature for Closed Loop Fuel Control - Code. I thought this was strange as I hadn't had an issue with this before.
Also I "Fixed "the P0330 Knock sensor 2 code and cleared the codes.
Doing so cleared the P0125 code for 1 day but it came back after a long drive. I also had a Pending P0133 -O-2 Sensor Circuit Slow Response and P0130 O-2 ,Oxygen Sensor.
Reset again.
The P0130 and P0133 didn't reappear the rest of the week but the P0125 did.
I monitored the Temperature using OBDwiz software and it appeared normal, maybe a Little cool so I replaced the T-Stat. Engine ran a little warmer, 10 Degrees, but this didn't solve the problem. Obviously the Temp sensor and wiring were working as it was being displayed on the Laptop
While monitoring the Temperature in the Log mode I also saw that the O-2 Sensor B1S1 was flat-lined, no voltage. It should have been the same as B1S2 O-2 sensor.
But no O-2 fault Codes were displayed only the P0125.
I discovered a broken wire at the O-2 B1S1 connector, Probably from tugging on it when installing, very hard to reach plug. Of course this is the one sandwiched against the firewall. I dug out the silicone boot, soldered a jumper wire in the connector hole, soldered jumper to the wire, heat shrink, epoxy and re-wrapped. Reset Code, took it on a reset drive and now its ready for emission testing.
The P0125 code being on when there really isn't an issue and not an O-2 sensor code must be a BUG in the programming and could lead one to replace T sensors, wiring, T-stats unnecessarily. Which I have read about in past posts.
I was getting P0135, O-2 Bank 1 Sensor 1 Heater circuit and P0330 Knock sensor 2 ECU Codes
I replaced the Bank 1 Sensor 1 O-2 sensor. After doing this I cleared the the Codes and the 0135 code went away,
Immediately I got the P0125, Insufficient Coolant Temperature for Closed Loop Fuel Control - Code. I thought this was strange as I hadn't had an issue with this before.
Also I "Fixed "the P0330 Knock sensor 2 code and cleared the codes.
Doing so cleared the P0125 code for 1 day but it came back after a long drive. I also had a Pending P0133 -O-2 Sensor Circuit Slow Response and P0130 O-2 ,Oxygen Sensor.
Reset again.
The P0130 and P0133 didn't reappear the rest of the week but the P0125 did.
I monitored the Temperature using OBDwiz software and it appeared normal, maybe a Little cool so I replaced the T-Stat. Engine ran a little warmer, 10 Degrees, but this didn't solve the problem. Obviously the Temp sensor and wiring were working as it was being displayed on the Laptop
While monitoring the Temperature in the Log mode I also saw that the O-2 Sensor B1S1 was flat-lined, no voltage. It should have been the same as B1S2 O-2 sensor.
But no O-2 fault Codes were displayed only the P0125.
I discovered a broken wire at the O-2 B1S1 connector, Probably from tugging on it when installing, very hard to reach plug. Of course this is the one sandwiched against the firewall. I dug out the silicone boot, soldered a jumper wire in the connector hole, soldered jumper to the wire, heat shrink, epoxy and re-wrapped. Reset Code, took it on a reset drive and now its ready for emission testing.
The P0125 code being on when there really isn't an issue and not an O-2 sensor code must be a BUG in the programming and could lead one to replace T sensors, wiring, T-stats unnecessarily. Which I have read about in past posts.
10-07-19, 06:47 AM
#2
+10 for crimping naked connectors and heat shrink.
Adding this; before applying heat shrink, pull test those wires. A good crimp won't let the wire move at all and it gives you confidence that your work is done right.
Tip: although we all grew up twisting wires before crimping and soldering, it's actually a no-no and weakens the connection. If the wire can be fed into the connector twist free, the wires are less likely to be cut during crimping. Look at the OEM work. There is no twisting there....
Adding this; before applying heat shrink, pull test those wires. A good crimp won't let the wire move at all and it gives you confidence that your work is done right.
Tip: although we all grew up twisting wires before crimping and soldering, it's actually a no-no and weakens the connection. If the wire can be fed into the connector twist free, the wires are less likely to be cut during crimping. Look at the OEM work. There is no twisting there....
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