P2602 Coolant pump control circuit low voltage

P2602 engine coolant pump circuit low

P2602 in short

P2602 means the computer sees low voltage in the electric coolant pump circuit. On the Honda Accord Plug-in and Hybrid, Honda says the pump may stick and set it. Owners report limp mode near 40 mph and a pump replacement. Drive carefully and have it inspected soon.

Some hybrids cool the engine with an electric pump instead of a belt-driven one. The computer watches the pump circuit and sets P2602 when it sees the voltage lower than expected.

Honda's service bulletin for the 2014 Accord Plug-in Hybrid says the electric water pump may stick and set P2602. A 2015 Accord owner whose dealer recorded low voltage for the electric water pump says the code returned within a day of a performance procedure.

Reference sites list a wiring short to ground and the pump relay as causes. One owner tested power, ground and signal at the pump and found them normal, which fits a pump fault rather than the wiring.

Most likely causes

  1. Electric coolant pump stuck or failing

    Supported by vehicle data
    Why it ranks here
    Honda's bulletin says the electric water pump may stick and set P2602, and Accord owners report dealers calling for a pump replacement.
    What would change this
    Rises if the pump does not run when commanded, or power, ground and signal at the pump are good. Falls if the pump runs normally and a wiring fault is found.

  2. Wiring short to ground or a faulty pump relay

    Possible — needs testing
    Why it ranks here
    A reference site lists a wiring short to ground and the pump relay as probable causes, but we found no make-specific confirmation.
    What would change this
    Rises if the circuit shows low voltage with the pump unplugged or the relay fails a test. Falls if circuit and relay are fine.

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 any coolant temperature or hybrid-system codes stored with P2602.

    Low riskTool: OBD-II scan tool

    • IfP2602 is stored and the car is limited in speed

      It meansDo not rely on the car; check the pump next.

      Go to step 2

  2. Have a shop check the coolant pump power, ground and control signal and whether it runs when commanded.

    Best left to a shopTool: multimeter, bidirectional scan tool

    Warning:Hybrid models have high-voltage cables, usually orange, and a hot cooling system. Leave the work to a shop and never open the cap on a hot system.

Symptoms

  • Check engine light with emissions or engine cooling system warnings
  • Car goes into limp mode and will not go much faster than 40 mph

Compare with: Check engine light with loss of power

How to fix

  1. With the engine cold, check that the coolant reservoir is between its marks, and book the car in rather than clearing the code.

On your vehicle

Honda

  • 2014–2015 · Accord

    Supported by vehicle data

    Honda's bulletin covers the 2014 Accord Plug-in Hybrid. Four 2014-2015 Accord and Accord Hybrid owners report P2602, speed limited to about 40 mph and pump replacement quotes. Bulletin status is not verified.

  • Honda Service Bulletin 10118171Status unverified

    MIL with P2602, electric engine coolant pump circuit low voltage

    2014accord · NHTSA 10118171

    The electric water pump may stick and set P2602 on the 2014 Accord Plug-in Hybrid.

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

No curated relationships for P2602 yet.

All Engine cooling (thermostat) codes

P2602 questions

Why is my Accord limited to 40 mph with P2602?

Owners with this code report limp mode at about 40 mph after the cooling system fault is flagged. Have the pump checked, because clearing the code often brings it back.

Sources and review

  1. Honda service bulletin, MIL with DTC P2602 (2014 Accord Plug-in Hybrid), NHTSA 10118171 — American Honda Motor Co.
  2. NHTSA complaint ODI 11243240 — NHTSA Office of Defects Investigation (owner complaint)
  3. NHTSA complaint ODI 11616936 — NHTSA Office of Defects Investigation (owner complaint)
  4. NHTSA complaint ODI 11210808 — NHTSA Office of Defects Investigation (owner complaint)
  5. P2602 trouble code definition — troublecodes.net
  6. NHTSA complaint ODI 10520128 — NHTSA Office of Defects Investigation (owner complaint)
Last reviewed
Written by
Saurabh K.
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