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Truck is throwing codes 21(o2 sensor/lean air-fuel ratio) and 52(knock sensor). I replaced the oxygen sensor with a Denso 237-1056, as recommended, and ran a new wire to the ECM. Scraped the old gasket off the manifold, cleaned with wire brush and brake cleaner to get a good ground for the single wire sensor. Still throwing the code, even after unplugging battery, main relay, and ECM fuse overnight.
Truck is throwing codes 21(o2 sensor/lean air-fuel ratio) and 52(knock sensor). I replaced the oxygen sensor with a Denso 237-1056, as recommended, and ran a new wire to the ECM. Scraped the old gasket off the manifold, cleaned with wire brush and brake cleaner to get a good ground for the single wire sensor. Still throwing the code, even after unplugging battery, main relay, and ECM fuse overnight.
Any suggestions?
It doesn't say there is a problem with your sensor it says the fuel mixture is wrong. You need to trouble shoot the fuel system.
It doesn't say there is a problem with your sensor it says the fuel mixture is wrong. You need to trouble shoot the fuel system.
Wow. I just checked the diag codes list again and 21 is listed as o2 sensor signal, not mixture. Gonna take some 80grit to the manifold, maybe it just isn't grounding.
Still having trouble grounding the oxygen sensor. I'm assuming that's what my problem is. Can I just run a wire from one of the O2 sensor studs to a grounds on the body or the engine?
Still having trouble grounding the oxygen sensor. I'm assuming that's what my problem is. Can I just run a wire from one of the O2 sensor studs to a grounds on the body or the engine?
What makes you so sure it's a ground issue and not a short or open wire?
Get your meter out!
Check resistance to battery ground post from sensor body.
Check for resistance to ground at the ECU end of the O2 sensor wire.
It's really low current just wiggling a couple of the nuts should do it.
...
It's also of course possible your new wire is in the wrong position (the diagram shows the backside of the plug, looking I to the ECU)
You have two digit codes, which is something an RTE ECU shouldn't be doing. I expect you have you new oxygen sensor wire in the HT signal spot and not OX, at best.
Did you run the wire full length from ECU to sensor, did you use a shielded wire?
Last edited by Co_94_PU; Sep 29, 2019 at 06:21 PM.
What makes you so sure it's a ground issue and not a short or open wire?
Get your meter out!
Check resistance to battery ground post from sensor body.
Check for resistance to ground at the ECU end of the O2 sensor wire.
It's really low current just wiggling a couple of the nuts should do it.
...
It's also of course possible your new wire is in the wrong position (the diagram shows the backside of the plug, looking I to the ECU)
You have two digit codes, which is something an RTE ECU shouldn't be doing. I expect you have you new oxygen sensor wire in the HT signal spot and not OX, at best.
Did you run the wire full length from ECU to sensor, did you use a shielded wire?
Originally Posted by Co_94_PU
This still doesn't jive for me. What does the sticker on that ecu look like..
I'll check the ECM on Wednesday. I used this wiring diagram when I ran the new (unshielded) wire all the way to the ECM. The new sensor came with 6"(?) of shielding, if that matters.
Just noticed on the left side pinout (hidden by my phone banner) VF is labeled "Check Connector Oxygen Sensor." Is this relevant?
Last edited by Theyseemespoolin; Sep 30, 2019 at 07:35 PM.
The early 22R-E (22R-TE) engine computers simply said 22R, meaning the 22R family of engines. The later ones did say 22R-E on the sticker.
I am pretty darn sure Toyota did not use the two-digit code system for the 1986 model year. My 1987 Factory Repair Manual only shows the single digit code system.
I want to say 1988 was around the time where the two digit code system started being used.
Last edited by old87yota; Oct 7, 2019 at 10:01 PM.
Reason: Correction
The early 22R-E (22R-TE) engine computers simply said 22R, meaning the 22R family of engines. The later ones did say 22R-E on the sticker.
I am pretty darn sure Toyota did not use the two-digit code system for the 1986 model year. My 1987 Factory Repair Manual only shows the single digit code system.
I want to say 1989 was around the time where the two digit code system started being used.
So why do you think my truck is throwing two digit codes?
So the 88 ECU is expecting the four wire oxygen sensor.
Switched power from main efi relay. Pin 2
Fixed ground, Pin 4
Ox output, pin 3
HT (ECU controlled heater), Pin 1
You can wire that up and put the four wire sensor on and the code 21 will go away. You should still be throwing lean codes since the fuel table isn't going to account for boost pressure.
You should source the right ECU, or invest in a standalone ECU.
Sep 27, 2019 | 01:49 PM
