P0598

Thermostat Heater Control Circuit Low

Q: Is it safe to drive with P0598?

Generally yes, but the engine may not reach or hold its ideal temperature. Watch the gauge and fix it soon to protect economy and emissions.

Q: Can I just clear P0598?

It will return until the heater circuit or thermostat is repaired. Clearing it alone won't restore proper temperature control.

Cooling system Generic OBD-II Medium

What it means

P0598 means the control circuit for the map-controlled thermostat heater is reading low voltage, so the ECM cannot electrically drive the thermostat as intended. This heater lets the ECM force the thermostat open sooner for better cooling and emissions control. A fault mostly affects coolant-temperature regulation rather than driveability.

Medium

Can I keep driving? Usually driveable, but keep an eye on the temperature gauge — poor coolant-temperature control can affect economy, emissions, and long-term engine health.

Real-world scan data

Seen in

130

scans in the past year

Found in

<0.1%

of scans

<0.1%

of scans that found faults

Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.

Common symptoms

What you'll notice

Check-engine light on
Engine temperature runs low or fluctuates
Reduced fuel economy
Cooling fans or warm-up behaviour acting abnormally

Common causes

Most likely first

Faulty map-controlled thermostat heater elementLikely
Open or short-to-ground in the heater control wiring (low voltage)Common
Loose or corroded connector at the thermostat heaterCommon
Failed engine control module (ECM), least likelyLess often

How to diagnose & fix

Work through it in order

Read freeze-frame data and confirm the heater control circuit reads low.
Inspect the thermostat heater connector and wiring for an open or short to ground.
Measure the heater element resistance against specification.
Repair the wiring or replace the map-controlled thermostat if the heater element is bad.
Clear the code and verify the ECM can command the heater normally.

FAQ

Quick answers

Is it safe to drive with P0598?+

Generally yes, but the engine may not reach or hold its ideal temperature. Watch the gauge and fix it soon to protect economy and emissions.

Can I just clear P0598?+

It will return until the heater circuit or thermostat is repaired. Clearing it alone won't restore proper temperature control.

Read & clear P0598 yourself

Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.

▶ Get it on Google Play

✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX