Fix P0097: Mechanic’s solutions that WORKED

The OBD2 code P0097 indicates a problem with the Intake Air Temperature (IAT) Sensor 2, specifically that the circuit is reporting a lower input than expected. This sensor measures the temperature of the air entering the engine’s intake system and is crucial for the engine control unit (ECU) to adjust the air-fuel mixture for optimal combustion. A low input signal could mean the sensor, or its circuit, is malfunctioning, potentially affecting engine performance.

P0097 quick overview

Meaning	P0097: Intake Air Temperature Sensor 2 Circuit Low Input
Is it serious?	Yes, it can impact engine efficiency, performance, and emissions.
Possible causes	– Faulty or damaged IAT sensor – Poor electrical connection in the IAT sensor circuit – Short to ground in the sensor circuit – Issues with the engine control module (ECM)
How to diagnose?	Inspect the IAT sensor and its connector for damage or corrosion Check the wiring and harness for shorts, opens, or poor connections Test the sensor’s voltage and ground supply for anomalies Replace the IAT sensor if it’s found to be defective Update or flash the ECM if necessary, especially if a glitch is suspected

How to fix P0097 – learn from mechanics

I looked into P0097 service cases at iatn.com website where in the private forums the mechanics seek advice from other mechanics. I looked up a bunch of cases to help you decide how to fix your issue and see what would a real mechanic do to solve it.

Case #1: Chevrolet

Vehicle Information 2006 Chevrolet C4500 Kodiak C4U042 6.6L

Issue + Repair History

• Customer bought truck at auction and serviced it, reported hard starting issue afterward.
• Turbo hold down bolts backed out, antifreeze leak at EGR cooler hose, oily charge air hoses, missing WIF sensor wiring.
• Fuel odor detected, fuel in radiator suspected.
• FRP pressure readings inconsistent.
• Codes retrieved: P0097 (intake air temp sensor 2 circuit low), P0230 (fuel pump circuit malfunction), P0463 (fuel level sensor circuit high).

Other OBD2 Codes + Test Results

• P0097: Intake Air Temp Sensor 2 Circuit Low.
• P0230: Fuel Pump Circuit Malfunction.
• P0463: Fuel Level Sensor Circuit High.

Mechanic Suggestions

• Consider replacing the fuel filter again, as the hard starting issue could be due to a leaking or faulty filter.
• Perform fuel system diagnostics, including checking fuel vacuum readings and high side leakages.
• Address potential shorted IAT sensor by unplugging it and checking for proper parameter readings.
• Verify the condition of glow plugs and inspect the rear injector harness wiring for any recalls.

Final Fix

• Decided to pull heads for inspection and replace head gaskets suspecting combustion crud in the radiator.

Case #2: Volvo

Vehicle Information 2006 Volvo S60 2.5T 2.5L

Issue + Repair History

• Previous repair involved the replacement of the mass air flow sensor due to hard MAF function fault codes.
• Continued issue with an IAT low signal fault persisting after MAF replacement.
• Replaced IAT/BPS sensor, but fault persisted.
• Suspected possible control unit glitch as a potential cause.

Other OBD2 Codes + Test Results

• P0097: Intake Air Temperature Sensor 2 Circuit Low
• IAT sensor reading: 14.75°C
• External temperature: 57°F

Mechanic Suggestions

• Check wiring harness for resistance from sensor to ECU to rule out wiring problems.
• Perform a hard battery reset to reset ECM adaptive learning.
• Clean throttle plate and PCV nipple to address potential idle quality issues.
• Verify 5V reference, ground, and signal wire integrity at the sensor wire with the key in position 2.
• Investigate the possibility of a software upgrade for the ECM to adjust parameters.
• Ensure that the correct sensor was replaced and consider checking the outside temperature sender in the mirror.
• Consider ECM upgrade to address potential ECM-275C ECT signal issue.
• Check for proper seating of the pins in the ECU box under the hood.
• Verify 5V reference at the IAT sensor to check for control unit issues.
• Investigate broken wires between the IAT and PCM as a potential cause for the low signal.

Final Fix

• Vehicle sent to the dealer where the PCM was flashed, resolving the issue.

Case #3: Chevrolet

Vehicle Information 2012 Chevrolet Impala LT 3.6L

Issue + Repair History

• Car exhibited loss of power and intermittent revving after a slight grade incident.
• Engine mounts and engine were replaced due to previous abuse.
• MAF replaced due to initial hard MAF function fault codes.
• Continued issue with intermittent loss of power and revving after a few miles of driving.
• Checked CAT, MAP, MAF, ignition switch, battery, alternator, ground, TAC, oil, and ATF levels.
• Found broken ignition voltage circuit connected to the trans fuse in the underhood fuse box due to broken engine mounts.

Other OBD2 Codes + Test Results

• P2534: Ignition on start switch circuit low voltage
• P0443: Purge solenoid valve control circuit
• P0102: MAF circuit low frequency
• P0097: IAT sensor 2 circuit low voltage
• Manifold vacuum readings at idle: 15 in.

Mechanic Suggestions

• Start with diagnosing the P2534 code: ignition on start switch circuit low voltage, as it may be related to other codes.
• Inspect the wheel speed sensors for potential issues.
• Check for one-way roller clutch failure, particularly if the issue is noticed in manual mode.
• Verify wiring harness integrity, as worn motor mounts may have caused damage.
• Perform load tests on sensor power and ground circuits, especially after the engine swap.
• Loosen gas cap to alleviate potential issues with the returnless fuel system.
• Constantly clear codes while simulating the fault to isolate the issue.
• Investigate potential trans relay issues and verify if the relay is integrated into the underhood fuse block.
• Check for potential transmission issues, particularly with gears 3-5-R.

Final Fix

• Discovered a broken ignition voltage circuit connected to the trans fuse due to broken engine mounts. Repaired the circuit to resolve the issue.

Diagnostic Step	Explanation
Inspect the IAT sensor and connector	Look for any physical damage or signs of corrosion.
Check the wiring and harness	Examine for shorts to ground, open circuits, or loose connections.
Test the sensor’s voltage and ground	Use a multimeter to ensure proper voltage and ground presence.
Replace the IAT sensor	If defective, replace it to restore accurate air temperature readings.
Update or flash the ECM	Consider if sensor replacement doesn’t resolve the issue or if there’s a known software glitch.

Addressing a P0097 code involves a careful examination of the IAT sensor system, ensuring that the sensor and its circuit are functioning correctly. Given the sensor’s role in managing air-fuel mixture, resolving this issue is crucial for maintaining efficient engine operation and preventing potential performance problems.