What Does P0121 Mean on a 2022 Mercedes-Benz GLE?
A P0121 code on your 2022 Mercedes-Benz GLE (W167) means the ECU has detected an irregular TPS signal. The voltage is within range but doesn't correlate with your driving inputs. Mercedes' engine management has identified a throttle system anomaly.
The 2022 GLE offers the M254/M264 2.0L turbo-four (GLE 350), M256 3.0L turbo-six with 48V ISG (GLE 450/GLE 580e PHEV), or M176 4.0L twin-turbo V8 (AMG GLE 63). All use direct injection. At 2-4 years old, both carbon buildup and software are viable suspects.
Top Causes of P0121 on the 2022 GLE
- Carbon buildup on throttle body – DI engines accumulate deposits. Likelihood: 35%
- ECU software calibration – Mercedes may have released updates. Likelihood: 25%
- Throttle body assembly issue – Internal TPS defect. Likelihood: 20%
- 48V/ISG interaction – Mild-hybrid transitions. Likelihood: 12%
- Connector or wiring issue – Corrosion or loose fit. Likelihood: 8%
Symptoms You May Notice
- Check Engine Light on MBUX
- Rough or inconsistent idle
- Hesitation during acceleration
- EQ Boost transitions feel rough
- Reduced power or limp mode
- Cruise control issues
How Serious Is This Code?
P0121 is medium severity. Your 2022 GLE remains drivable with potential performance reduction. Address it soon—within 1-2 weeks.
Diagnostic Steps
- Scan with XENTRY or Mercedes-compatible tool
- Check ECU software version and updates
- Inspect throttle body for carbon
- Monitor TPS and ISG data
- Check connector and wiring
- Test for boost leaks
Estimated Repair Costs
- Under warranty: $0 (4-year/50,000-mile warranty likely active)
- Throttle body cleaning: $150–$350
- Throttle body replacement: $600–$1,100
- ECU update: $150–$250 (if out of warranty)
Can You DIY This Fix?
DIY feasibility is low. Check warranty first—the 2022 GLE should still be under Mercedes' 4-year/50,000-mile warranty. If covered, let the dealer handle it. The GLE's engine bay varies significantly by engine option—V8 models are particularly tight.