B1022

Code

MITSUBISHI B — Body

Air thermo sensor high

Brand: MITSUBISHI

Type: B — Body

Views: UK: 10 EN: 19 RU: 13

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Faulty air temperature (thermistor) sensor
Open or high-resistance wiring or connector (broken wire, corrosion, poor pin contact)
Short to battery/constant 12V (less common)
Poor or missing ground at HVAC control module or sensor
Water intrusion or contamination of sensor/connector
HVAC control module fault or internal circuit failure

Symptoms

DTC B1022 stored and possibly lamp or HVAC warning on dash (model dependent)
Incorrect or no cabin/ambient temperature reading on climate control display
Poor automatic HVAC temperature control (blows too hot or too cold)
A/C compressor cycling or operation affected when system uses sensor input
Intermittent HVAC behavior if wiring is intermittent

What to check

Retrieve freeze-frame data and live sensor value with a scan tool
Visually inspect sensor location and connector for corrosion, contamination, water, and damaged insulation
Check that sensor is properly seated and clip/retainer intact
Wiggle test wiring while watching live data for intermittent changes
Measure supply voltage and ground at the sensor connector with key on
Measure sensor resistance (remove connector) at ambient temperature and compare to specification

Signal parameters

Sensor type commonly a thermistor (NTC): resistance falls as temperature rises
Typical mid-range: ~10 kΩ at 25 °C (varies by manufacturer) — consult vehicle service manual for exact values
Expected voltage to module generally within ~0.2–4.8 V depending on temp and circuit; exact values vary by model
Open-circuit/very high resistance often yields a high-voltage reading or out-of-range value reported by control module
Short-to-ground presents as near 0 V; short-to-12 V or open may appear as voltage above normal range (>4.8–5 V)

Diagnostic algorithm

Confirm DTC and note freeze-frame/live data using a scan tool
Perform visual inspection of sensor, connector, and wiring harness for damage or contamination
With ignition ON (engine off), measure reference supply voltage and ground at the sensor connector; compare to expected spec
Unplug sensor and measure sensor resistance at ambient temperature; compare resistance to service data or expected NTC curve (if unavailable, compare to typical NTC behavior: resistance decreases with increasing temperature)
If resistance is out of range or infinite, replace the sensor and re-test
If sensor resistance is within expected range, backprobe connector with sensor connected and measure signal voltage while changing air temperature near sensor (warm and cool) to confirm sensor response
Perform continuity check from sensor connector back to HVAC control module; repair any opens or high-resistance circuits
Repair or replace damaged wiring or connector pins (use sealed connectors or dielectric grease where appropriate to prevent corrosion)
If wiring and sensor test good but fault persists, inspect/replace HVAC control module or its connectors per factory service procedure
Clear codes and perform functional test/road test; verify code does not return

Likely causes

Sensor open-circuit or degraded thermistor element
Connector corrosion or bent/broken terminal(s) causing intermittent/high resistance
Wire chafing or break near harness end-points
Pins pushed out of connector housing or trapped by debris
Module input stage failed after water exposure or electrical event

Fault status

⚠️ Status

Air thermo sensor high — air temperature sensor circuit reporting abnormally high voltage or open/high-resistance condition. Check sensor, wiring, and HVAC control input.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours

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B1022 — Air thermo sensor high