P0099 OBD-II Trouble Code: Intake Air Temperature Sensor 2 Circuit Intermittent/Erratic

Our certified mechanics come to you · Get a fair and transparent estimate upfront

Red-stars EXCELLENT RATING ON

Cost of diagnosing the P0099 code

P0099 is a diagnostic trouble code (DTC) for "Intake Air Temperature Sensor 2 Circuit Intermittent/Erratic". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic for $114.99 . Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $20.0 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.

Cars Estimate Credit towards follow-up repair Earliest Availability
Ford $114.99 $20.0
Toyota $114.99 $20.0
BMW $124.99 $20.0
SCHEDULE P0099 DIAGNOSTIC Get a fair and transparent estimate upfront

P0099 code definition

Intake Air Temperature Sensor 2 Circuit Intermittent/Erratic

What the P0099 code means

P0099 is the OBD-II generic code that indicates that the engine control module (ECM) has detected a fault in the intake air temperature sensor 2 (IAT2). This code indicates that it is not operating in the normal sensor range and that the IAT2 has intermittent or erratic sensor input to the ECM.

What causes the P0099 code?

  • The erratic or intermittent IAT input causes the ECM to not trust the input reading and substitutes its input to 70° F.

  • The intake air temperature sensor 2 is not accurate within 2 degrees when compared to the engine coolant and the mass air temperature sensors when the engine is cold started after the engine has been off for more than 5 hours.

  • The intake air temperature sensor 2 is not within specification range within 2 degrees of the sensor when compared to the mass air flow sensor when started warm and heat soaked from 10 seconds to 30 minutes.

What are the symptoms of the P0099 code?

  • The Check Engine Light comes on to alert of a problem with the system.
  • The engine may run rough, hesitate, or surge while driving depending on ambient temperature difference from 70° F.

How does a mechanic diagnose the P0099 code?

  • Visually checks the electrical connections and wire harness to the intake air temperature sensor.

  • Scans and documents engine codes and checks freeze frame data for when the sensor failed.

  • Scans the IAT2 sensor and compares the output to be within specifications for when it fails in the freeze frame data to try and duplicate the sensor failure. They will lightly tap the sensor to see if the reading is erratic.

  • Disconnects the IAT2 sensor connector and verifies that the temperature reading goes below -4° F.

  • Shorts the two connector wires together to see if temperature readings go above 212° F.

  • While the connectors are shorted, they will do a wiggle test to see if any issues are found with the wiring or connections.

  • Using a multimeter to check that the ohms of the IAT2 sensor is within specifications while lightly tapping on sensor to see if the reading is erratic indicating a sensor internal failure.

  • Replaces the sensor if the sensor fails the wiggle test or is not within specifications.

Common mistakes when diagnosing the P0099 code

  • Not verifying failures by clearing the codes and testing to see if the problem returns
  • Not verifying freeze frame readings and wiggle testing the sensor for the failure
  • Replacing parts before conducting pinpoint tests and visual checks

How serious is the P0099 code?

  • The ECM will substitute a 70° F sensor input for the out of specification reading for the sensor.

  • The engine may run rough or hesitate if outside temperature is more than 10° F different from the 70° F the ECM uses as a substitute output.

  • The engine can hesitate and have a lack of power during acceleration depending on how different the outside temperature is from the default 70° F.

  • The engine will fail emission testing due to the Check Engine Light being on and the monitors not completed.

What repairs can fix the P0099 code?

  • Replacing the IAT2 sensor if it fails testing
  • Repairing or replacing the wiring or connection to the IAT2 sensor
  • Repairing the ECM connector or replacing the ECM

Additional comments for consideration regarding the P0099 code

The IAT2 code P0099 can be caused from corrosion in the connector that is causing the connection to go in and out but stays in specification when it does work. Sometimes a sensor has loose connections internally that can be duplicated during testing and lightly tapping on the sensor.

Need help with a P0099 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

Check Engine Light
P0099
trouble codes

No more waiting rooms! Our mechanics will come to you to diagnose and fix the P0099 code.

SCHEDULE P0099 DIAGNOSTIC
Get a $20 credit for the follow-up repair

Recent Check Engine Light is on Inspection reviews

Excellent Rating

(7400)

Rating Summary
6879
249
58
41
173
6879
249
58
41
173
 at YourMechanic

David

13 years of experience
393 reviews
David
13 years of experience
Chevrolet Malibu L4-2.4L - Check Engine Light is on Inspection - Marietta, Georgia
He explained everything to me in detail on what I needed to know about my car. Definitely recommend him for getting the job done.
 at YourMechanic

Raymond

37 years of experience
402 reviews
Raymond
37 years of experience
Toyota Camry L4-2.2L - Check Engine Light is on - Las Vegas, Nevada
Raymond did a great job however I was charged for two hours labor and he was only here less than 45 minutes. should I expect this on future appointments with your mechanic ?
 at YourMechanic

Shane

17 years of experience
217 reviews
Shane
17 years of experience
Volkswagen EuroVan V6-2.8L - Check Engine Light is on Inspection - Austin, Texas
Arrived on time. Explained the issues he found and how he will fix it. I have parts on order and will schedule an appointment to have Shane install the parts when they arrive.
 at YourMechanic

Kanstantsin

19 years of experience
51 reviews
Kanstantsin
19 years of experience
Ford F-150 V8-4.6L - Check Engine Light is on Inspection - Littleton, Colorado
Kanstantsin arrived early. Was very courteous and professional. Will highly recommend to anyone. Thank you Kanstantsin.


More related articles

P2703 OBD-II Trouble Code: Transmission Friction Element D Apply Time Range/Performance
P2703 P2703 code definition A P2703 trouble code means that the Powertrain Control Module (PCM) has detected a malfunction in the transmission friction element D application. In addition to the storage of a trouble code and the illumination of the...
P0334 OBD-II Trouble Code: Knock Sensor 2 Circuit Input Intermittent (Bank 2)
P0334 P0334 code definition The P0334 Trouble Code indicates that the knock sensor on a cylinder is not working according to the manufacturer’s specifications. What the P0334 code means The code means that there is a problem with one of...
P2757 OBD-II Trouble Code: Torque Converter Clutch Press Control Solenoid Control Circuit Performance or Stuck Off
P2757 means a problem with the torque converter clutch pressure control solenoid due to a bad torque converter or solenoid or electrical issues.

Related questions

Code p0128
Code P0128 (https://www.yourmechanic.com/article/p0033-obd-ii-trouble-code-turbo-charger-or-supercharger-bypass-valve-control-circuit-by-john-nelson) is engaged specifically when the engine itself does not get to operating temperature in a specified time period. The only things that can cause this problem is an issue with the thermostat (https://www.yourmechanic.com/services/thermostat-replacement), head temp sensor, and...
Check engine light turns on and off
Both of these codes are related to the oxygen sensor readings. More often than not, this will be caused by failing oxygen sensors (https://www.yourmechanic.com/services/oxygen-sensor-replacement). There could be other issues that can cause these codes, such as an engine misfire, failing...
My 2001 chevy venture shuts off on me at random times . A couple of days the check engine light was on so we hooked the computer u
It's not unusual for code P0420 to come on, stay on for even a few days, and then just disappear. Then, months later, it might happen again (i.e., appear and disappear). If this is the circumstances you face, I would...

How can we help?

Our service team is available 7 days a week, Monday - Friday from 6 AM to 5 PM PST, Saturday - Sunday 7 AM - 4 PM PST.

1 (855) 347-2779 · hi@yourmechanic.com