355 OBD2 codes P1117 and P1121

I know that these codes are for the heating element in the post-cat O2 sensors, left and right.

Problem is, I've replaced both O2 sensors; in fact, all 4 sensors (pre-cat and post-cat) have been replaced with new sensors. These are new codes after the replacement of all sensors.

The codes come up as pending codes quite quickly after clearing codes, and this behavior can be repeated. I've even tried disconnecting the battery, waiting overnight, reconnecting, getting the car up to temp, and then doing the 10 minute ECU learn procedure. The pending codes will be there after the idle session.

And, I've even driven the car, hoping they are just spurious pending codes, but eventually the Check Engine light turns on with these codes set.

Any ideas? What's the next thing to try? Could the cats be bad? (No Slow Down lights have come on) Could I have gotten two bad O2 sensors? (odds seem unlikely)

 

Did you at least clean the connectors and inspect them visually for integrity?

 

Have the O2 sensors in correctly?

Bosch 13819 Pre cat
Bosch 13820 Post cat

 

Did you check the fuses for the heating circuits?

 

First, why did you replace all the O2 sensors? Let's start there. Then, the codes you are getting are for the O2 sensor heater circuit shorted to ground. You have to find the source of the short. They may indicate that the O2 sensor fuses have blown. Or you may have the wrong O2 sensors which have too low a heater resistance. You need to check the fuses and wiring for the sensor heaters. Additionally, you state that the codes are pending which means they problem was sensed once but not confirmed. The CEL should not come on when the codes are pending. That the CEL comes on is an indication that the fault has been sensed repeatedly.

 

O2 sensors were replaced because there were other codes for the O2 sensors before. When I get O2 sensor codes, I like to replace all 4 O2 sensors.

As for the pending/set codes: The codes are pending almost immediately after an erase. However, after drive cycles, eventually the CEL turns on and the codes are actually set (not pending).

I did check the fuses for the O2 sensors (heating circuits), and can you believe this? The RH side fuse was MISSING.

Fuse was replaced. Hopes were high. Let it idle for 10 minutes. Same result: P1117 and P1121.

I got some offline advice that one of the thermocouple ECUs might be bad. So, I'm swapping ECUs from a known good car into this one, and I'll report the result.

 

I'd be surprised if the cat ECUs have anything to do with it, but then, it's a Ferrari.

Check to make sure you have voltage on the B+ lead to the O2 heater. Check the heater resistance. Make sure you have the correct O2 sensors. If they are not correct and the heater element resistance is too low it could trigger the CEL due to excessive current draw.

 

O2 sensors are correct parts, and I have verified that each one is plugged in to the correct connector.

I will check voltage and resistance next, after trying a swap of the thermocouple ECUs.

 

As johnk predicted, thermocouple ECUs did not have any effect.

 

Does the car have high flow cats?

 

Don't know, will look. Why would that make a difference?

 

Yes it will make a big difference,with high flow cats you need the 90 degree extenders on the post cat o2 sensors so you dont get a check engine light.

 

The cats should not make a difference regarding these codes. P1117 and 1121 are electrical in nature.

This may be of help

[ame]http://www.youtube.com/watch?v=HPFz97zi6_M[/ame]

 

John
Yes they will if they are high flows.I got both codes with my tubi high flow cats.When i put on the 90 degree extenders no more codes for over 50000km.

 

Yup. Been there, done that. Extenders on HF Cats work wonders.

Wiring the O2 sensors and Thermocouples correctly helps too, haha

 

I would expect 0422 and 0432 if there were a problem with HF cat or test pipes.

 

I'm installing hyperflows this weekend and never had those codes before. I'll be on the lookout though.

 

How about checking the grounds for the O2 sensors. We add ground wires on our 348s.

 

I've confirmed that everything is wired correctly. All of the part numbers are correct. Electrical connections are clean and test correctly.

There _are_ high-flow cats on this car. O2 sensor extenders were installed, and the codes do not return.

Of course, now, I have to drive the car for a while, but it looks like the problem is hopefully solved!

I owe all of you a virtual beer, or a real one if you come down to Houston... Thanks for everyone's help. What a great community.

 

What did you change? The extenders.? Anything else?

 

Yes. Other than installing new O2 sensors, which caused the P1117 and P1121 codes, the only thing that I changed was adding the extenders to the post-cat O2 sensors.

 

+1

 

Maybe you just needed the extenders ?

 

Maybe. However, there were different codes before I replaced the O2 sensors, indicating that the sensors themselves were the problem.

P1117 and P1121 only occurred after the O2 sensors were all changed.

 

John both codes po422 bank 1 post cat and po432 bank2 post cat are right
But codes p1117 is the same as po422 and p1121 is the same as code po432.I think its because some codes are generic and others are manufacturer codes but they mean the same thing.It also depends on your scanner..