What Does P1119 Mean?
P1119 indicates the Engine Coolant Temperature (ECT) sensor circuit is producing an intermittent low voltage signal, or the secondary IAT-B circuit has a low input. This is functionally similar to P1114 and may be a manufacturer-specific variant. The intermittent low voltage makes the ECM perceive an overheated engine condition, potentially triggering unnecessary fan operation, reduced power modes, and incorrect fuel strategy during warm-up.
Common Causes
30%
Intermittent short to ground in the ECT sensor wiring
25%
ECT sensor developing intermittent low internal resistance
20%
Coolant contamination in the ECT sensor connector causing leakage to ground
15%
IAT-B sensor (if applicable) signal circuit shorted low
10%
ECT sensor wiring harness pinched or chafed against engine block
Diagnostic Steps
1
Step 1: Monitor ECT sensor reading during a cold start. If it intermittently reads extremely high temperatures (230°F+) when the engine is actually cold, the signal voltage is dropping too low.
2
Step 2: Inspect the ECT sensor connector for coolant leaks or contamination from the thermostat housing or cylinder head. Coolant on the connector is a common cause of ground leakage.
3
Step 3: Disconnect the ECT sensor and check resistance. Compare to manufacturer specifications for the current actual temperature. Low or erratic resistance confirms sensor failure.
4
Step 4: With the sensor disconnected, check signal wire isolation from ground using a multimeter. Any low resistance to ground indicates a harness short.
5
Step 5: Replace the ECT sensor and clean or replace the connector if contaminated. Repair any coolant leaks at the sensor bung to prevent recurrence.
Estimated Repair Cost
$30 - $200
Parts + labor, varies by vehicle and location
P1119 indicates the Engine Coolant Temperature (ECT) sensor circuit is producing an intermittent low voltage signal, or the secondary IAT-B circuit has a low input. This is functionally similar to P1114 and may be a manufacturer-specific variant. The intermittent low voltage makes the ECM perceive a...
The most common cause of P1119 (Engine Coolant Temperature (ECT) Sensor Circuit Intermittent Low Voltage/IAT - B Circuit Low Input) is: Intermittent short to ground in the ECT sensor wiring
Typical repair costs for P1119 range from $30 to $200, depending on the vehicle, location, and whether you do it yourself or go to a shop.
False high-temperature readings may engage limp mode or reduced power unexpectedly, which can be startling in traffic. Conversely, if the ECM ignores a genuine overheat due to signal credibility issues, engine damage could result.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1119 to identify the root cause.
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Quick Info
Category
Powertrain
System
Engine Management / Cooling System Monitoring
Difficulty
Type
Manufacturer
Recommended Tools
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