Engine code
P0118: Coolant temperature signal too high
How this range is built
| Part of the job | Low | High |
|---|---|---|
| Parts | $15 | $60 |
| Labor: 0.6 to 1 hours × $125 to $175 an hour | $75 | $175 |
| Fees: shop supplies, disposal, diagnostics | $10 | $25 |
| Total, rounded | $100 | $260 |
The hourly rate is the BLS Occupational Employment and Wage Statistics, May 2025 average pay for this trade in Boston, $31.54 an hour, times 4 to 5.5 to cover what a shop bills (overhead, tools, insurance, profit). Parts are a band from budget aftermarket to the manufacturer part. Full method.
Not a repair shop, estimates only. Typical range, estimate. Not a quote. Your car, parts and shop change the number.
This is the range for the most common fix, coolant temperature sensor replacement. Which repair your car needs depends on a proper diagnosis.
The coolant temperature sensor tells the computer how hot the engine is. It now reports a temperature that is extremely high, or its wire is shorted, which looks the same to the computer. The computer may be fooled into running the fan on high and trimming the fuel mixture incorrectly.
- Safe to drive?
- Usually yes, for now
- Most common cause
- Failed coolant temperature sensor
If the gauge is truly climbing, stop and let it cool; otherwise short drives are okay while you get it checked.
What you may notice
- Hard starting when cold
- Rich fuel smell
- Fan running often
- Gauge reading wrong
Common causes, most likely first
- Failed coolant temperature sensor
- Shorted wiring
- Corroded connector
- Truly overheating engine
- Low coolant
Check this first
Compare the dash gauge to how the engine feels. If it really is hot, stop and treat it as an overheating problem.
Other repairs that sometimes fix P0118
| Repair | Typical range, Boston |
|---|---|
| Thermostat replacement | $120 to $470 |
| Radiator replacement | $320 to $1,125 |
| Water pump replacement | $310 to $1,275 |
Before you pay
- Ask the shop what test showed this part is the cause, not just that the code appeared.
- Ask for parts and labor listed separately, and for the hours.
- Ask for a written OK before any extra work. Massachusetts rules require written authorization before repairs.
Got a quote already? Check it against the range. Want to see if your car has a recall tied to this problem? Check recalls by VIN.
Need to read a code yourself? OBD-II scanners on eBay (affiliate link, disclosure).
P0118 questions
Is my engine actually overheating?
Not necessarily. A bad sensor or shorted wire can make the computer think so. Check the dash gauge and look at the coolant level when cold. If the gauge is normal, the sensor is the more likely culprit.
Why is it hard to start cold?
The computer thinks the engine is already warm, so it skips the extra fuel a cold engine needs. The result is long cranking or a rough start on cold mornings, even though the engine is actually cold.
Should I keep driving?
Only if the temperature gauge reads normal and no steam or sweet smell shows. If the gauge climbs or you see steam, pull over safely and let the engine cool, since overheating can ruin it.
How much does it cost to fix P0118?
The most common fix, coolant temperature sensor replacement, has a typical range of $100 to $260 in Boston. It is an estimate built from parts prices and local labor wages, not a quote. Your car and shop change it.
Related codes
- P0117: Coolant temperature signal too low
- P0128: Engine not warming up fast enough
- P0125: Engine slow to warm up for normal fuel control
More engine codes
Code meaning written in our own words. Some codes mean different things on different makes, so check your scan tool or manual. Not a repair shop, estimates only.