87702-ZW9-800 Honda MARK, FAST IDLE (Honda Code 6643712).

Table 1
Diagnostic Trouble Codes for High Intake Manifold Air Temperature
J1939 Code Code Description Comments
172-16 Engine Air Inlet Temperature : High - moderate severity (2) The engine has been running for 3 minutes.
No other 172 codes are active.
168 codes are not active.
The intake manifold air temperature exceeds the value that is programmed into the ECM for 8 seconds. The code is logged.
This code will be reset when the temperature is less than 122° C (252° F) for 4 seconds. Probable Causes
Coolant level
Air-to-air aftercooler (ATAAC) (if equipped)
Cooling fan
Air inlet and exhaust system
Ambient temperature
Altitude
Running condition
Intake air from a heated areaRecommended Actions
Note: The procedures have been listed in order of probability. Complete the procedures in order.
Table 2
Troubleshooting Test Steps Values Results
1. Coolant Level
A. Check that the coolant is filled to the correct level.
Note: If the coolant level is too low, air will get into the cooling system. Air in the cooling system will cause a reduction in coolant flow.
Coolant
Result: The coolant level is low.
Repair: Fill the coolant system to the correct level. Refer to the Operation and Maintenance Manual, "Coolant Level - Check".
Result: The coolant level is OK.
For engines with an aftercooler, proceed to Test Step 2.
For engines with no aftercooler, proceed to Test Step 3.
2. Air-to-Air Aftercooler (ATAAC) (If Equipped)
A. Check the ATAAC for debris or damage.
Note: Debris between the fins of the ATAAC core restricts air flow through the core.
ATAAC
Result: The ATAAC has excessive debris or is damaged.
Repair: Clear the debris from the ATAAC or replace the ATAAC.
Result: The ATAAC is OK.
Proceed to Test Step 3.
3. Cooling Fan
A. Check the operation of the cooling fan.
Note: A fan that is not turning at the correct speed can result in insufficient airflow through the aftercooler core.
Cooling fan
Result: The cooling fan is not operating correctly.
Repair: Investigate the cause of the incorrect fan operation
Result: The cooling fan is operating correctly.
Proceed to Test Step 4.
4. Air Intake and Exhaust System
A. Check the air intake and exhaust system for the following defects:
Blockages
Restrictions
Damage to the air intake ducts and hoses
Loose connections and air leaks
B. Check for active diagnostic codes:
107-15: Engine Air Filter 1 Differential Pressure high - least severe (1)
107-16: Engine Air Filter 1 Differential Pressure high - moderate severity (2)
Air intake and exhaust
Result: The air intake or exhaust system is blocked, restricted, damaged, or loose.
Repair: Make all necessary repairs to the air intake system.
Result: The air intake and exhaust system is OK.
Result: A 107-15 or 107-16 code is active
Repair: Refer to Troubleshooting, Inlet Air is Restricted.
Proceed to Test Step 5.
5. Ambient Temperature
A. Check for a high ambient temperature.
Note: When outside temperatures are too high, there is insufficient temperature difference between the outside air and the intake air.
Ambient Temperature
Result: The ambient air temperature is high.
Repair: Operate the engine at reduced speed or reduced power.
Result: The ambient air temperature is OK.
Proceed to Test Step 6.
6. Altitude
A. Check for operation at high altitude.
Note: The cooling capacity of the ATAAC is reduced as the engine is operated at higher altitudes.
Altitude
Result: The engine is being operated at high altitude.
Repair: Operate the engine at reduced speed or reduced power.
Result: The engine is not being operated at high altitude.
Proceed to Test Step 7.
7. Running Condition
A. Check that the engine is not operating in the lug condition.
Note: When the load that is applied to the engine is too large, the engine will run in the lug condition. When the engine is running in the lug condition, engine rpm does not increase with an increase of fuel. This lower engine rpm causes a reduction in coolant flow through the system.
Running condition
Result: The engine is operating in the lug condition.
Repair: Reduce the load on the engine.
Result: The engine is not operating in the lug condition.
Proceed to Test Step 8.
8. Intake Air from a Heated Area
A. Ensure that the air inlet system is not receiving air from a heated area.
Intake air temperature
Result: The intake air is from a heated area.
Repair: If necessary, relocate the air supply to the intake manifold to the outside of the engine enclosure.
Check for air leaks in the pipe between the air inlet and the inlet to the turbocharger compressor.
Result: The intake air is not from a heated area.
Contact the Dealer Solutions Network (DSN).