P26A6 Engine coolant bypass valve A: the valve position sensor reads too low

Engine coolant bypass valve position sensor circuit low

Severity not verified — if the car runs badly, have it inspected

The Ram and Subaru bulletins for this code say the check engine light comes on and give a repair, but neither rates the risk or says how the car drives, so we have not set a class. Because the valve steers coolant, watch the temperature gauge.

It gets more serious if:

  • Stop: The temperature gauge reads hot, a high-temperature or pull-over warning appears, or steam comes from under the hood. Pull over somewhere safe, stop the engine and let it cool before deciding what to do. Never open the radiator cap or coolant reservoir while the engine is hot; escaping coolant can scald.

Source: how we rate severity

P26A6 in short

P26A6 means the engine computer sees the position sensor on the engine coolant bypass valve reading too low. Ram has traced it to a broken gear inside the 3-way coolant valve on 2022-2023 Ram 1500, and Subaru has a diagnostic correction for it. Treat the temperature gauge as the thing to watch until it is checked.

The coolant bypass valve is an electrically driven valve that sends coolant through or around parts of the cooling system. It has a built-in position sensor so the engine computer can see whether the valve moved where it was told. P26A6 sets when that position signal sits lower than the allowed range.

Ram and Subaru both use the same wording for this code: bypass valve A, position sensor circuit low. Ram has a bulletin that lists it together with P26A3 and P2681 and replaces the 3-way coolant valve because of a broken internal gear. Subaru has issued a correction to its service manual for diagnosing P26A6 and its high-side partner P26A7.

The bulletins we found do not say how the car drives with the code set or what the most common failure is on Subaru, so this page stays modest about severity and about causes beyond the Ram valve.

Most likely causes

  1. Coolant bypass valve assembly (broken internal gear or failed position sensor)

    Supported by vehicle data
    Why it ranks here
    FCA bulletin 07-005-24 lists P26A6 with P26A3 and P2681 on 2022-2023 Ram 1500 and replaces the 3-way coolant valve for a broken internal gear. The NHTSA record is an unverified summary and covers Ram only.
    What would change this
    Rises on a Ram 1500 of those years when P26A3 or P2681 are stored too. Falls if the valve moves normally when commanded and the signal is steady.

  2. Wiring or connector fault in the valve position sensor circuit

    Possible — needs testing
    Why it ranks here
    The code describes a low signal on the position sensor circuit, which a wiring or connector fault can also produce. Subaru issued a corrected diagnostic procedure for the code, so a shop is expected to test the circuit before replacing the valve. No bulletin we read names a wiring fault.
    What would change this
    Rises if the connector is damaged or the sensor voltage is low only at the connector end. Falls if the circuit tests normal and the valve itself is at fault.

What to test first

Start at step 1. Each result tells you what it means and where to go next.

  1. Read all stored codes and note whether P26A3, P26A7 or P2681 are stored with P26A6.

    Low riskTool: OBD-II scan tool

  2. Ask a dealer whether a bulletin applies to your VIN. Ram 07-005-24 covers 2022-2023 Ram 1500 and Subaru 09-132-25 covers 2019-2025 Forester, 2020-2025 Legacy and Outback, and 2021-2025 Impreza and Crosstrek.

    Low risk

    • IfA bulletin applies

      It meansFollow its diagnostic or repair procedure.

      Go to step 3

    • IfNone applies

      It meansThe circuit still needs testing.

      Go to step 3

  3. Have a shop test the position sensor signal and reference voltage at the valve connector and watch the valve move when commanded.

    Best left to a shopTool: scan tool with bidirectional control, multimeter

    Warning:The valve sits in the coolant circuit. Do not open any coolant line or the radiator cap on a hot engine; escaping coolant can scald.

Symptoms

  • Check engine light on
  • Temperature gauge reads hot or a high-temperature warning appears Gets more serious: stop and have it checked.

How to fix

  1. Ask a dealer whether Ram bulletin 07-005-24 or Subaru bulletin 09-132-25 applies to your VIN.

  2. Keep an eye on the temperature gauge until the code is diagnosed.

Parts and cost context

  • Engine control module (ECM / PCM):The bypass valve is a separate part from the engine computer; the computer is only the module that reads its position sensor. Labor varies; get a quote.

Labor varies by vehicle and shop; get a quote before you approve a repair.

Compare used part prices on PartPriceGuide

On your vehicle

Ram

  • 2022–2023 · 1500

    Supported by vehicle data

    FCA bulletin 07-005-24 covers P26A6 with P26A3 and P2681 and replaces the 3-way coolant valve for a broken internal gear. The NHTSA record is an unverified summary.

  • 07-005-24Status unverified

    Broken internal coolant valve gear, P26A3, P26A6 and P2681

    2022–20231500 · issued · NHTSA 11001237

    Replace the 3-way coolant valve when the MIL is on and one or more of these codes is set. Only the NHTSA summary was read.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

Subaru

  • 2019–2025

    Supported by vehicle data

    Subaru bulletin 09-132-25 corrects the service manual diagnosis for P26A6 and P26A7 on Forester, Legacy, Outback, Impreza and Crosstrek. It does not name a cause in the summary we read.

  • 09-132-25Status unverified

    Service manual correction: diagnosing P26A6 and P26A7

    2019–2025forester, legacy, outback, impreza, crosstrek · issued · NHTSA 11016215

    Corrects the manual diagnostic procedures for the two position-sensor codes; the repair steps are in the bulletin. Only the NHTSA summary was read.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • P26A3Engine coolant bypass valve A range or performance problem

    Same system Supported by vehicle data

    Ram lists P26A3 (range or performance) and P26A6 in the same bulletin, which replaces the 3-way coolant valve.

  • P2681Engine coolant bypass valve A control circuit open or out of range

    Same system Supported by vehicle data

    Ram lists P2681 (valve control circuit open) with P26A6 in the same bulletin.

All Engine cooling (thermostat) codes

P26A6 questions

Is P26A6 the same as P26A7?

No. Subaru names P26A6 as the bypass valve position sensor reading too low and P26A7 as reading too high. Its bulletin 09-132-25 covers both.

Sources and review

  1. FCA 07-005-24: Broken internal coolant valve gear, P26A3/P26A6/P2681 — FCA US / NHTSA ,
  2. Subaru 09-132-25: Service manual correction for DTCs P26A6 and P26A7 — Subaru of America / NHTSA ,
  3. 2023 Integra Owner's Manual: How to Handle Overheating — American Honda Motor Co.
  4. Toyota Camry Owner's Manual (OM06291U, 2.5L A25A-FKS / 3.5L 2GR-FKS) — Toyota
  5. 2019 Ranger Workshop Manual 303-03 Engine Cooling 2.3L EcoBoost: Description and Operation (Fail Safe Cooling) — Ford Motor Company
Last reviewed
Written by
Saurabh K.
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