P1121

Code

MAZDA P — Powertrain

Throttle Position Sensor Signal Not Consistent With Mass Air Flow Signal

Brand: MAZDA

Type: P — Powertrain

Views: UK: 25 EN: 38 RU: 35

AI status

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Page language: EN

Contaminated or faulty MAF sensor
Faulty or out-of-spec throttle position sensor (TPS)
Damaged wiring or poor connectors for TPS or MAF (open, short to ground/voltage)
Intake air leaks (vacuum leaks, cracked hoses, bad intake boots)
Sticking or dirty throttle body or throttle plate
Incorrect sensor grounding or power supply (5V reference issues)

Retrieve freeze frame and live data PIDs with a capable scan tool (TPS %, TPS voltage, MAF g/s or V, calculated load, RPM)
Compare TPS position vs MAF response: slowly open throttle and watch MAF and TPS increase together—look for delays, drops, or inconsistent behavior
Check for related stored codes (P0100–P0104 series for MAF, P0120–P0124 series for TPS)
Visually inspect MAF and TPS connectors and wiring for corrosion, breaks, or pin damage
Perform a smoke or smoke/soapy spray test to find intake leaks between MAF and throttle body
Inspect and clean the MAF sensor with approved MAF cleaner if contaminated; allow to dry before reinstalling

TPS: reference ~5 V supply; signal ~0.3–1.0 V at closed throttle, ~4.0–4.5 V at wide open (varies by model)
MAF: output may be voltage (0–5 V), frequency, or direct mass flow (g/s); value should increase smoothly with throttle/RPM
TPS and MAF signals should change proportionally: small throttle openings produce small increases in MAF; smooth correlation across opening range
Watch for noise/spikes on signals which indicate wiring or sensor grounding issues

Connect scan tool and record live data for TPS (%) or V, MAF (g/s or V), RPM, and fuel trims; note freeze-frame data for P1121
Perform a dynamic correlation test: with engine idling, slowly open throttle and observe both MAF and TPS. Document any lag, dropouts, or non-linear response
Visually inspect and wiggle wiring and connectors for intermittent faults while monitoring live data
Check for intake leaks: use smoke machine or spray around intake boots and check for RPM/MAF changes
Clean the MAF with approved MAF cleaner if dirty; retest—do not touch sensor elements
Measure TPS reference voltage and ground at the sensor connector; measure TPS signal voltage at closed and wide-open positions and compare to expected ranges
If TPS signal is out of range or intermittent, replace or calibrate TPS as required; if engine uses electronic throttle, follow manufacturer relearn/initialization procedures after replacement
If MAF output is erratic or out-of-range, verify wiring and power, then replace MAF if necessary
Clear codes and road-test to confirm the fault does not recur; if it does, consider ECU fault or intermittent wiring harness damage and perform pinpoint testing or consult manufacturer service data
If aftermarket software/tunes present, return to stock calibration and retest

Contaminated/dirty MAF causing incorrect airflow reading
TPS out of calibration or intermittent TPS signal
Intake leak between MAF and throttle body causing low measured airflow for given TPS
Wiring/connectors with corrosion or intermittent contact

⚠️ Status

TPS signal does not correlate with MAF airflow signal — inconsistent sensor inputs detected

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-2.5 hours

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P1121 — Throttle Position Sensor Signal Not Consistent With Mass Air Flow Signal