What Does P1622 Mean?
The engine coolant temperature sensor signal is within valid voltage range but shows implausible values compared to other engine temperature inputs. The PCM detects a rationality or performance issue with the ECT sensor.
Common Causes
40%
Failing ECT sensor with degraded thermistor element providing inaccurate readings
25%
Low coolant level causing sensor to read air temperature instead of coolant
15%
Thermostat stuck open or removed causing engine to run too cool
12%
High resistance in sensor wiring or connections causing signal degradation
8%
Air trapped near sensor location preventing accurate temperature reading
Diagnostic Steps
1
Step 1: Check coolant level in radiator and reservoir - top off and bleed air from system if low
2
Step 2: Monitor ECT sensor reading with scan tool from cold start through full warm-up - should show smooth rise from ambient to 195-220°F
3
Step 3: Compare ECT reading to intake air temperature and actual coolant temperature with infrared thermometer
4
Step 4: Test ECT sensor resistance while engine warms up - resistance should decrease smoothly as temperature rises
5
Step 5: Check thermostat operation by monitoring upper radiator hose temperature - should warm up when thermostat opens
Estimated Repair Cost
$100 - $400
Parts + labor, varies by vehicle and location
The engine coolant temperature sensor signal is within valid voltage range but shows implausible values compared to other engine temperature inputs. The PCM detects a rationality or performance issue with the ECT sensor.
The most common cause of P1622 (Engine coolant temperature signal range/performance) is: Failing ECT sensor with degraded thermistor element providing inaccurate readings
Typical repair costs for P1622 range from $100 to $400, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Engine may run inefficiently with poor fuel economy and emissions. Extended operation may cause engine damage if actual overheating condition is masked by faulty sensor.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1622 to identify the root cause.
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Quick Info
Category
Powertrain
System
Engine Management/Cooling System
Difficulty
Type
Manufacturer
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