Code 21, 28, 71 intermittent (1 Viewer)

[fzj80tlc]

I have 94 FZJ80 with 170K that has been running rough, especially at idle, sometimes 400 rpm, with gas smell. I took to dealer and pulled code 71 and most likely needed a new VSV. I decided to do more of my own research first.

After searching forum, I checked codes but had none. I took intake manifold off and checked each of the 4 switches underneatth (VSV's and others) and they all seemed to work, all would cycle open/close when 12V applied. So I decided while to replace plugs, wires, cap and rotor. Running seemed okay at times, but maybe not perfect. I checked O2 sensors, by unplugging and plugging and it showed the code 21 and 28, respectively. Then ran well for 20 ish miles, no codes. New tank of gas on a 3hr drive and after about 60 miles, code 21, 28, 71. I drove another 100 miles and CEL off. Return 3 hr drive no CEL for 2hrs, then fill up gas and code 21, 28, 71. After short 10 mile, off again.

Please let me know suggestions. Replace O2 sensors, check EGR system and vacuum tubing, check EGRf modulator filter, etc. I've read a number of posts, but want to now best place to start.

Thanks,
Mike

 

[fzj80tlc]

Any suggestions?

I've noticed that even thought their is no CEL, it does smell like very rich gas exhausting.

Mike

 

[stockfj80]

Did you replace both o2 sensor with quality one from the dealer or NTK brand? Code 21 and 28 is for the o2 sensor. Code 71 is the EGR. There a few writeup on how to clean the EGR passage and defeat the code.

 

[Brentbba]

'94's are notorious for eating O2 sensors for breakfast, lunch, dinner and a late night snack. Replace them with OEM. This model year had a recall for this very issue. You can see if yours were replaced under this recall - send your vin and inquiry to cruiserdan and he can check for you. OEM O2's aren't cheap, but years of reading this board has told me that they are worth it compared to aftermarket.

 

[stockfj80]

My o2 lasted me 18 years and 224,000 miles so spending $150 for 2x NTK sensors is not a bad hit in the wallet.

 

[fzj80tlc]

Thanks guys. I am looking into replacing the 02 sensors now with Cruiser Dan? I will post again after replacement.

Just curious, is it common to have this intermittent code issue?

Best,
Mike

 

[ampline]

Thanks guys. I am looking into replacing the 02 sensors now with Cruiser Dan? I will post again after replacement.

Just curious, is it common to have this intermittent code issue?

Best,
Mike

Sorry to bring up an old thread. I've got the exact same codes. Did you ever fix this? If so, what was the cause. Thanks