P2181: Cooling system not holding its expected temperature
Cooling system performance
Severity: Inspect soon
The code does not say whether the engine is running too hot or too cold. Kelley Blue Book advises not to drive until it is inspected because overheating can destroy an engine.
It gets more serious if:
- Stop: Stop if the temperature gauge is high, a hot-engine message shows, or steam or a coolant smell appears.
P2181 in short
P2181 means the engine temperature is not behaving as the computer expects, either too hot or too cold. A thermostat stuck open or closed, low coolant, or a bad coolant temperature sensor are the usual causes. Check the gauge, and have it inspected before driving far.
The computer compares measured coolant temperature with what it should be after a given amount of engine run time and airflow. If the temperature is outside that range, it sets P2181, and the code does not say which direction.
A thermostat stuck open or closed, low coolant, other cooling parts or a coolant temperature sensor that reads wrong can all do this.
GM has notes for some vehicles. On the 2013 Malibu, plastic flashing or debris in the water outlet can cause overheating messages with P2181, and on some 2011 Savana and Express vans the rear heater pipes should be checked for correct installation after a cold-start P2181.
Most likely causes
Cause 1: Thermostat stuck open or closed
Common general cause- Why it ranks here
- Kelley Blue Book lists a thermostat stuck open or closed among the main causes.
- What would change this
- Rises if the engine warms very slowly or overheats. Falls if warm-up is normal.
Cause 2: Low coolant or a leak
Common general cause- Why it ranks here
- KBB lists low engine coolant first.
- What would change this
- Rises if the reservoir is low or there is a leak. Falls if the level is correct.
Cause 3: Coolant temperature sensor reading wrong
Common general cause- Why it ranks here
- KBB lists a faulty coolant temperature sensor giving incorrect readings.
- What would change this
- Rises if the scan tool temperature disagrees with a thermometer or the gauge. Falls if it matches.
Cause 4: Debris in the water outlet, or misrouted rear heater pipes (some GM vehicles)
Supported by vehicle data- Why it ranks here
- GM PIC5764 points to plastic flashing or debris in the water outlet on the 2013 Malibu, and GM PIP4775B points to the rear heater pipes on some 2011 Savana and Express vans. Only NHTSA summaries were read.
- What would change this
- Rises if you drive an affected GM model and the part is found obstructed or wrong. Falls on other vehicles.
What to test first
Start at step 1. Each result tells you what it means and where to go next.
Step 1: With the engine fully cool, check the coolant level, then start the engine and watch whether the temperature gauge climbs normally, stays low, or runs high.
Warning:Never open the radiator or reservoir cap on a hot engine; hot coolant can scald.
IfThe coolant is low
It meansFind and fix the leak, then top up and recheck.
IfThe gauge runs high
It meansStop driving; the engine is overheating.
IfThe gauge stays low or never warms fully
It meansThe thermostat may be stuck open.
Step 2: Compare scan tool coolant temperature with the gauge and, if possible, an infrared thermometer reading at the thermostat housing.
IfThe readings disagree
It meansThe sensor or wiring is suspect.
IfThe readings agree but the engine is too hot or too cold
It meansTest the thermostat and cooling parts.
IfThe car is a 2013 Malibu or 2011 Savana/Express
It meansAsk about the GM notes for the water outlet and heater pipes.
Points to: Debris in the water outlet, or misrouted rear heater pipes (some GM vehicles)
Symptoms
- Check engine light on
- Poor heater output or slow warm-up (running cold)
- Poor fuel economy
- Temperature warning, steam or coolant smell (running hot) Gets more serious: stop and have it checked.
How to fix
Step 1: With the engine fully cool, check the coolant level in the reservoir and top up with the coolant your manual specifies.
Warning:Never open the cap on a hot cooling system.
Step 2: Ask a dealer whether your VIN has a bulletin for P2181.
Parts and cost context
- Thermostat:Find out whether the engine is running hot or cold before replacing parts. Labor varies; get a quote.
Labor varies by vehicle and shop; get a quote before you approve a repair.
Compare used part prices on PartPriceGuideOn your vehicle
ChevroletYour car
2013 · Malibu
Supported by vehicle dataGM PIC5764 covers overheating messages with P00B7 or P2181 on the 2013 Malibu, with the check being the water outlet. Whether it is still current is not verified.
2011 · Express
Supported by vehicle dataGM PIP4775B covers P2181 shortly after a cold start, with the rear heater pipes to be checked. Whether it is still current is not verified.
PIC5764Status unverified
Overheating messages with P00B7 or P2181
2013malibu · NHTSA 10112486
Check the water outlet at the rear of the cylinder head for plastic flashing or debris and clean or replace it.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.
PIP4775BStatus unverified
Service engine soon shortly after cold start with P2181
2011express · NHTSA 10112520
Inspect the rear heater pipes for correct installation.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.
PontiacYour car
2009 · G3
Supported by vehicle dataGM PIP4599D has the thermostat heater tested for P2181 and the thermostat replaced if the coolant does not reach 195 F within 5 minutes. Whether the bulletin is still current is not verified.
PIP4599DStatus unverified
P2181 set; test the thermostat heater
2009g3 · NHTSA 10112684
If coolant does not reach 195 F (90 C) within 5 minutes, replace the thermostat and check calibrations are current.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.
VolkswagenYour car
2014 · Touareg
Supported by vehicle dataVolkswagen TB011410 gives an engine computer programming update for P2181. Whether the bulletin is still current is not verified.
TB011410Status unverified
Update programming, MIL on, P2181 stored in ECM
2014touareg · NHTSA 10241313
Engine computer programming update.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.
Related codes
No curated relationships for P2181 yet.
P2181 questions
Does P2181 mean my engine is overheating?
Not necessarily. It means the temperature is outside the expected range, either too hot or too cold. Check the gauge to tell which.
Can I drive with P2181?
Kelley Blue Book advises not to until it is inspected. If the gauge is normal, keep it short, and stop if it climbs.
Sources and review
- P2181 code: cooling system performance
- PIC5764: Overheating messages with P00B7 or P2181
- PIP4775B: Service engine soon shortly after cold start with P2181
- PIP4599D: P2181 set; test the thermostat heater
- TB011410: Update programming, MIL on, P2181 stored in ECM
- Last reviewed
- Written by
- Saurabh K.
- Editorial review
- Pending
- Technician review
- Technician review pending
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