Engine Retarder Control Circuit High
This code indicates a problem with the engine retarder control circuit being too high.
Heads up: this code wasn't in our hand-written library yet, so DiagCoach AI built this page on the fly. Double-check critical specs against service info before condemning parts.
What it means (plain English)
The engine retarder, which helps slow down the vehicle without using the brakes, sees a voltage level or signal that's too high—around 5 volts instead of the expected 0.5 to 1.5 volts, indicating either a circuit fault or a sensor issue.
What the computer is actually seeing
The ECM detects an unexpected high voltage signal from the engine retarder control circuit, usually above 4.5 volts.
What a healthy reading looks like
Normal voltage for the engine retarder control signal should be between 0.5 to 1.5 volts under normal operation.
Guided diagnostic — the DiagCoach way
Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.
- 11. Check the wiring and connectors for the engine retarder control circuit for damage or corrosion. Decision: Are the connections secure and in good condition? If yes, proceed to step 2; if no, repair as needed.
- 22. Measure the voltage at the engine retarder control module while the engine is running. Decision: Is the voltage between 0.5 to 1.5 volts? If yes, further diagnosis is required; if no, proceed to step 3.
- 33. Inspect the engine retarder control module for faults and test its functionality. Decision: Does the module operate correctly? If yes, the issue may be elsewhere; if no, replace the module.
Common causes
- Damaged wiring or connectors in the engine retarder circuit
- Faulty engine retarder control module
- Short circuit in the electrical system
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's moderate severity; you can drive short distances but should address it soon to avoid brake wear or other issues.
Will the code come back after clearing?
If the underlying issue isn't fixed, yes, the code will likely return.
Why does this code pair with SPN 1335?
SPN 1335 is related to low voltage in the same engine retarder control circuit, indicating a potential circuit issue.
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