What Does P011B Mean?
The ECM has determined that the engine coolant temperature and intake air temperature readings do not correlate properly under conditions where they should agree, such as after an extended cold soak. When the engine has been off long enough for all components to reach ambient temperature, both sensors should read within a few degrees of each other. A large discrepancy indicates one sensor is reading incorrectly.
Common Causes
35%
Faulty intake air temperature (IAT) sensor reading too high or too low compared to actual ambient conditions
30%
Faulty ECT sensor reading incorrectly at cold soak conditions, skewing the correlation check
20%
Wiring issue on IAT or ECT circuit introducing resistance offset that shifts the reading at cold temperatures
15%
Heat soak condition near the IAT sensor from exhaust or engine bay retained heat causing premature reading divergence
Diagnostic Steps
1
With the vehicle cold-soaked overnight, compare ECT and IAT readings on a scan tool before starting the engine. Both should be within 10°F (5°C) of each other and close to the actual ambient temperature measured with an infrared thermometer.
2
If one sensor reads significantly different from ambient, disconnect that sensor and measure its resistance. Compare to the manufacturer's resistance chart for the current ambient temperature.
3
Check for aftermarket intake modifications, missing ducting, or relocated IAT sensors that may expose the sensor to engine bay heat rather than incoming ambient air.
4
Inspect connectors and wiring for both sensors, checking for corrosion, water intrusion, or damaged terminals that could add resistance to the circuit.
5
If both sensors read correctly in isolation, clear the code and monitor during the next cold start. Some vehicles set this code due to software calibration issues that may require a PCM reflash.
Estimated Repair Cost
$50 - $300
Parts + labor, varies by vehicle and location
The ECM has determined that the engine coolant temperature and intake air temperature readings do not correlate properly under conditions where they should agree, such as after an extended cold soak. When the engine has been off long enough for all components to reach ambient temperature, both senso...
The most common cause of P011B (Engine Coolant Temperature/Intake Air Temperature Correlation) is: Faulty intake air temperature (IAT) sensor reading too high or too low compared to actual ambient conditions
Typical repair costs for P011B range from $50 to $300, depending on the vehicle, location, and whether you do it yourself or go to a shop.
This code primarily affects cold-start fuel calculations and emissions. The vehicle may run richer or leaner than intended during warm-up, increasing emissions and slightly reducing fuel economy, but it does not pose a direct safety hazard.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P011B to identify the root cause.
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Quick Info
Category
Powertrain
System
Engine Cooling & Air Intake System
Difficulty
Type
Generic (SAE)
Recommended Tools
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