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2016 Dodge Challenger Scat Pack P1217 and P121B Codes After Installing Flowmaster Cat-Back Exhaust

Model: 2016 Dodge Challenger Fault Code: P1217 Posted: 2016-07-12 10:42

Hi everyone, I'm looking for help with a recurring issue on my 2016 Dodge Challenger Scat Pack. After installing a Flowmaster cat-back exhaust system, the Check Engine Light (CEL) came on. Multiple shops have been consulted, but none could identify or resolve the problem. Flowmaster provided a video guide suggesting that the fault lies with the exhaust valve actuator installation—specifically, the springs and washers. We reinstalled these components as instructed, but the issue persists. The vehicle is showing two specific OBD2 codes: P1217 (Active Exhaust Valve 1 Performance) and P121B (Active Exhaust Valve 2 Performance). I'm wondering if this is a known issue with aftermarket exhaust systems on the 2016 Challenger, or whether it's related to improper actuator installation or wiring. I've heard about a Technical Service Bulletin (TSB) for these codes—does anyone know if it involves a reflash of the Powertrain Control Module (PCM)? Also, since I replaced only the exhaust system (excluding catalytic converters), could this be causing interference with the ECU's exhaust valve control? I don't have access to a diagnostic scanner or a bidirectional tool. Could someone advise on what steps to take next? Is it safe to assume that removing the codes via tuning will fix the issue, or might this lead to future engine problems?

Related fault codes

P1217

Comments (7)

Anonymous 2016-07-12 10:57

P1217 and P121B refer to Active Exhaust Valve 1 and 2 Performance issues. These codes are commonly linked to exhaust valve actuator malfunctions. I recommend contacting your local Dodge dealership—there is a known TSB for these codes, which may involve a software reflash. Note: Warranty eligibility depends on the vehicle's build date; this information should be provided when reaching out.

Anonymous 2016-07-12 16:16

I took my car to the Dodge dealership and they diagnosed it but advised me to return to where I purchased the Flowmaster exhaust. It seems they either lack expertise or are unwilling to address issues related to aftermarket parts. The vehicle is not under warranty because the modification was aftermarket.

Anonymous 2016-07-12 16:40

Right or wrong—was it clear that installing aftermarket exhaust components would void the manufacturer's warranty? Regardless, I believe the TSB for these codes involves a PCM reflash. I'll check the official documentation and get back with more details tomorrow.

Anonymous 2016-07-12 19:10

BS? No—this isn't about an acceleration sensor. I've spoken to several people here. One suggestion is to perform a tuning adjustment and clear the codes. Would a Diablosport or a Mopar PCM reflash solve this issue? Any insights would be appreciated.

Anonymous 2016-07-13 07:40

I think I understand why Dodge might have referenced Flowmaster—did you remove the original exhaust valves during your installation? To clarify: Did you install new exhaust valves into the modified pipes, or did you retain sections of the original system? Do you have a bidirectional OBD2 scanner? Before investigating wiring circuits, please check fuse #36 (Electronic Exhaust Valve) located in the trunk. This is part of the ECU circuit and could be a contributing factor. If you don't have access to a diagnostic tool, consider checking with a professional who has one.

Anonymous 2016-07-13 19:25

I replaced the entire exhaust system (excluding catalytic converters). The car runs well in terms of performance—though it's running slightly rich. However, the CEL remains on. I'm concerned about whether this could lead to long-term engine or emission issues. I don't have a diagnostic scanner, so I'm relying on community advice.

Anonymous 2016-07-14 07:14

If the Check Engine Light is on, the vehicle is not running properly. First, verify that the exhaust valve actuators were installed in their original positions—left and right sides are indexed and must be correctly aligned. If the actuators are properly reinstalled, a technician should be able to perform diagnostics—but only with an OBD2 scanner. Without one, it's difficult to confirm whether the issue lies in wiring or actuator function.