What Does P0121 Mean on a 2020 Nissan Murano?
A P0121 code on your 2020 Nissan Murano tells our diagnostic investigators that the throttle position sensor (TPS) is sending voltage within the normal range but with an abnormal performance pattern. The ECM compares TPS data to accelerator pedal input, airflow readings, and engine load—and finds a mismatch.
The 2020 Murano runs the 3.5L VQ35DE V6 (260 hp) with a CVT. This naturally aspirated V6 uses multi-point (port) injection, which gives the throttle body a cleanliness advantage over direct-injection engines. The electronic throttle body contains the integrated TPS. At 4-6 years old, maintenance-related causes become the primary concern.
Common Symptoms to Watch For
- Check engine light illuminated
- Hesitation during acceleration, especially from stops
- Rough or surging idle
- CVT feels sluggish or jerky
- Reduced power when loaded with passengers
- Slightly decreased fuel economy
Top Causes Ranked by Likelihood
- Carbon buildup on throttle body (40%) – PCV gases and oil vapor deposit carbon on the throttle bore at this age and mileage. Port injection slows the rate but doesn't eliminate it. Cost: $150–$300.
- Throttle body assembly wear (25%) – TPS resistive element wear creating dead spots or erratic voltage. Cost: $280–$500.
- Wiring or connector corrosion (20%) – Engine bay heat from the V6 and years of environmental exposure degrade the connection. Cost: $80–$250.
- ECM calibration issue (10%) – A missed software update. Cost: $100–$175.
- Intake manifold gasket leak (5%) – Age-related gasket deterioration. Cost: $200–$400.
How Serious Is This Code?
P0121 is medium severity. The Murano is a premium crossover often carrying families—reliable acceleration matters for merging and passing. Fix this soon.
Diagnostic Path
Monitor live TPS voltage during slow throttle sweeps with a scan tool. Expect 0.5V closed, 4.5V wide-open. Look for dead spots or sudden voltage changes. Inspect the throttle body for carbon by removing the intake tube. Check the connector for corrosion.
Can You Fix This Yourself?
Your 2020 Murano may still be within Nissan's 5yr/60k powertrain warranty. If out of warranty, throttle body cleaning on the VQ35DE is a moderate DIY job—the throttle body is accessible from the top. After cleaning: ignition ON 3 seconds, start, idle 10 minutes. DIY feasibility: moderate.
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