P2121 and P2122 OBD codes, "Reduced Engine Performance" message, engine will not rev above 1,000 RPM in Drive on 2004 S6

ericbeatty43 · Post by **ericbeatty43** » 06 Jan 2025, 11:16

Hello everyone. I'm brand new to this community/forum. The subject line above summarizes my situation but here's a more expansive description.

My daughter's 2004 S60 2.5T with automatic transmission went into Limp Mode a couple of weeks ago and became virtually undrivable. It starts up just fine and idles normally BUT it will not rev above 1Krpm when placed into Drive. It won't go above 8-10 mph on level ground and is absolutely incapable of climbing the slight incline in our driveway.

We've had this car for nearly 8 years now and this is the first time that we've ever had any issues with it. All work on it has been strictly maintenance/upkeep - oil/fluid changes, brakes, etc. Never anything performance or operability related. Hence, Ic diagnostic tools don't own/have any Volvo-specific diagnostic tools like the VIDA system that I see mention a lot online. All I have is a simple OBDII scanner to read codes.

Anyhow, when the "Reduced Engine Performance" message appeared in the little window at the lower left corner of the dash, it was NOT accompanied by any CELsymbol lighting up on the dash.

Nevertheless, I used my OBDII scanner to read the car and got 4 codes: P2121, P2122, P2121pd, and P2122pd.

Looking those up online pointed me to several communities (including this one) that indicated that the engine throttle body or the accelerator pedal assy with buit-in position sensor were the likely culprits.

I have replaced both of those - first the throttle body assy - then the pedal assembly - with no change in results.

I have also read that the wiring/connectors for these units can be susceptible to corrosion so I made certain to thoroughly clean the connectors with CRC Electrical Contact Cleaner when disassembling and reassembling things. Further, I purchased an ECU removal tool and carefully unseated the computers, carefully cleaned the connectors and sockets, and then reassembled them.

Again, still nothing changed. At this point, I am absolutely stymied. I am posting this in order to seek far more knowledgeable help. Is there anything that I potentially missed or overlooked?

I ALWAYS made sure to perform all the electrical/electronic component replacements, cleaning, etc. with the battery fully disconnected. Is there any procedure that I might have not known about to reset the ECU and clear out the "Reduced Engine Performance" message? Will not clearing that message from the computer prevent the system from operating correctly, even with the new parts installed?

I'm hoping beyond hope that you folks can guide me to the solution. Once again, the P2121 and P2122 codes are the ONLY codes that the car is generating (as far as I can tell from my simple OBDII scanner).

Thanks in advance for any tips, sugestions, theories, ideas, etc. that you can share with me.

Cheers,

Eric

Post by **cn90** » 06 Jan 2025, 11:31

What is the odometer reading?

ericbeatty43 · Post by **ericbeatty43** » 06 Jan 2025, 11:54

cn90 wrote: ↑06 Jan 2025, 11:31 What is the odometer reading?

Approximately 188,000 miles

Post by **jonesg** » 07 Jan 2025, 15:43

If its in limp mode Vida will show why.
You already spent more money on the wrong parts than a vida setup costs.
If you own a laptop you can buy vida on a thumb drive($100) with its own operating system, all you need is a JRL cable.
Google boot&go.

ericbeatty43 · Post by **ericbeatty43** » 07 Jan 2025, 16:01

jonesg wrote: ↑07 Jan 2025, 15:43 If its in limp mode Vida will show why.
You already spent more money on the wrong parts than a vida setup costs.
If you own a laptop you can buy vida on a thumb drive($100) with its own operating system, all you need is a JRL cable.
Google boot&go.

Can you share a link to where to obtain these? I'd sure appreciate it. Thanks in advance!

Post by **scot850** » 08 Jan 2025, 06:56

https://diaglaptops.com/wp/vida2go/

Neil

ericbeatty43 · Post by **ericbeatty43** » 08 Jan 2025, 07:43

scot850 wrote: ↑08 Jan 2025, 06:56 https://diaglaptops.com/wp/vida2go/

Neil

Thanks! Very helpful!

Post by **firstv70volvo** » 08 Jan 2025, 09:04

Have you checked the fuses in the engine compartment? I read one of the fixes for these codes was replacing a blown 10A fuse (slot 11?) in the engine compartment, It's the fuse for the accelerator pedal sensor, cooling fan for electronics box engine compartment and AC compressor solenoid switch. I don't have a wiring diagram for the S60 so not sure about the slot number of the fuse, it's slot 8 for my 2001 V70 but someone said it's slot 11 for the S60, just not sure but it's not difficult to check all the fuses in the engine compartment. Does your AC compressor work?

ericbeatty43 · Post by **ericbeatty43** » 08 Jan 2025, 11:25

firstv70volvo wrote: ↑08 Jan 2025, 09:04 Have you checked the fuses in the engine compartment? I read one of the fixes for these codes was replacing a blown 10A fuse (slot 11?) in the engine compartment, It's the fuse for the accelerator pedal sensor, cooling fan for electronics box engine compartment and AC compressor solenoid switch. I don't have a wiring diagram for the S60 so not sure about the slot number of the fuse, it's slot 8 for my 2001 V70 but someone said it's slot 11 for the S60, just not sure but it's not difficult to check all the fuses in the engine compartment. Does your AC compressor work?

Thank you. I'll definitely check those this afternoon and report back later.

ericbeatty43 · Post by **ericbeatty43** » 09 Jan 2025, 08:19

firstv70volvo wrote: ↑08 Jan 2025, 09:04 Have you checked the fuses in the engine compartment? I read one of the fixes for these codes was replacing a blown 10A fuse (slot 11?) in the engine compartment, It's the fuse for the accelerator pedal sensor, cooling fan for electronics box engine compartment and AC compressor solenoid switch. I don't have a wiring diagram for the S60 so not sure about the slot number of the fuse, it's slot 8 for my 2001 V70 but someone said it's slot 11 for the S60, just not sure but it's not difficult to check all the fuses in the engine compartment. Does your AC compressor work?

I checked my fuses and discovered that slot #8 fuse is the one that controls the throttle pedal sensor and the AC clutch. AND it was blown! So I immediately replaced it and started the car but nothing had changed.

So, I took a look at that fuse again and discovered that the replacement I had just installed 5 minutes earlier was also blown. I found another 10A replacement and repeated the process. Yep, that fuse also blew! Having now exhausted my supply of 10A fuses, I ordered some more from Amazon (they're out for delivery right now) and did some additional Google-ing. Once it is lighter out, I'm going to disconnect the wiring connector to the A/C compressor clutch and try replacing the fuse yet again to see if it continues to blow. Wish me luck!