At idle, expect 1.0-1.5V corresponding to 15-21 inHg vacuum. With engine off and key on, sensor should read 4.5-4.7V (atmospheric pressure). On a 50ms/div timebase, visible intake pulse oscillations of 0.1-0.2V amplitude should be present at idle, frequency matching engine RPM. Snap throttle should show immediate rise to 4.3-4.6V with smooth, rapid return to idle vacuum.

At idle with engine fully warmed, expect 0.9-1.3V corresponding to 2-4 g/s airflow. Voltage should increase smoothly and linearly with throttle opening, reaching 3.8-4.5V at wide-open throttle. No fluctuations or noise greater than 0.05V should be present. During snap throttle, response should be immediate with no lag or steps in the voltage transition.

At idle, injector pulse width of 2.5-3.5ms with battery voltage (13-14V) when off. Sharp drop to near 0V during injection event, followed by negative spike of -40V to -65V when injector closes due to inductive kickback. The closing spike indicates proper pintle seating and healthy coil winding. Current ramp should be smooth without steps or irregularities.

Battery voltage (13-14V) during dwell time of 3-4ms at idle, followed by sharp drop to near 0V at spark event. After firing, expect 3-5 oscillations (ringing) at 150-250V peak amplitude lasting 1-2ms. Dwell time increases with RPM, and waveform should be consistent across all four cylinders.

Initial firing spike of 15-25kV at idle with fresh plugs, followed by horizontal spark line at 2-4kV lasting 1.5-2ms. Spark line should be relatively flat with minimal slope. After spark extinction, expect 4-6 coil oscillations decaying to baseline. All cylinders should show firing voltage within 3kV of each other.

Narrow-band zirconia sensor post-catalyst shows relatively stable voltage between 0.65-0.85V centered around 0.7-0.8V when catalyst is functioning properly. Signal should be much flatter and slower-responding than upstream sensor due to oxygen storage capacity of healthy catalyst. Very slow, lazy oscillations (once every 3-5 seconds) are normal. Voltage should remain fairly constant during fuel control changes that cause upstream sensor to switch rapidly.

Wideband air-fuel ratio sensor maintains relatively steady voltage around 3.0-3.3V during closed-loop operation at idle. Unlike narrow-band sensors, it does not oscillate rapidly but instead provides proportional voltage across full AFR range. Voltage responds quickly (under 100ms) to commanded fuel changes during snap throttle tests. During cold start enrichment, voltage will read higher (3.5-3.8V indicating rich) and stabilize to 3.0-3.3V once entering closed loop.

Digital square wave with varying pulse widths for position identification, switching between 0.3V and 4.7V. At 800 RPM idle, cam sensor frequency is half of crank (16.5Hz). Pattern shows distinct varying pulse widths that repeat every two crankshaft revolutions, allowing PCM to identify each cylinder.

Clean digital square wave alternating between near 0V (0.2V) and near 5V (4.8V) with sharp transitions. At idle (800 RPM), frequency should be approximately 33Hz with consistent pulse width. The missing tooth gap should appear once per crankshaft revolution, showing two consecutive missing pulses clearly.

Two separate continuous DC voltage signals that move opposite directions. At closed throttle (idle), TPS1 reads 0.55-0.85V while TPS2 reads 4.15-4.45V. At wide open throttle, TPS1 reads 4.2-4.6V while TPS2 reads 0.9-1.3V. The sum of both sensors should equal approximately 5V at any throttle position, with smooth linear transitions and no dead spots.

Active Hall-effect sensors produce a clean digital square wave signal that switches between approximately 0.3V (low) and 4.7V (high) with sharp rise and fall times. At 30mph, expect 60-65Hz; at 60mph, expect 125-135Hz. All four wheel speed sensors should show nearly identical frequency when driving straight, with differences less than 2-3Hz indicating matched tire diameters and proper operation.

Vehicle speed is transmitted as a digital value over the CAN-C bus from the ABS/ESC module to other control modules. The CAN bus should show continuous differential voltage activity with CAN High at 3.5V and CAN Low at 1.5V during dominant bits (2V differential). Speed data packets are transmitted approximately every 20ms with vehicle speed encoded as a 16-bit value in km/h.

At cold start (68°F/20°C), expect approximately 2.5-3.0V that smoothly decreases to 0.5-0.7V as engine reaches operating temperature (195°F/90°C). The voltage decline should be gradual and linear without sudden jumps or drops, taking approximately 5-8 minutes to reach normal operating temperature.

At ambient temperature (68°F/20°C), expect 2.5-3.0V that closely tracks actual air temperature in the intake. After engine shutdown on a hot day, voltage may drop to 1.5-2.0V as underhood temperature rises (heat soak). The sensor should respond quickly to temperature changes, typically within 30-60 seconds.

2021 Hyundai Tucson Waveform References

Airflow Sensors

Fuel System

Ignition System

Oxygen Sensors

Position Sensors

Speed Sensors

Temperature Sensors