P1620 — MIL Requested by the Throttle Unit (ECM-532D) - faulty signal
CAUTIONIs it safe to drive? Drive gently and get it looked at soon — it can worsen or fail inspection.
What P1620 means
This is a manufacturer-specific code — its meaning depends on the vehicle’s make (see below).
What P1620 means on specific makes
Volvo CAUTION
Volvo-specific. On later Volvos, internal code ECM-532D (surfaced as P1620 by some readers) means a sub-diagnostic inside the throttle/ECM requested the MIL. It's a pointer code — the real fault is whatever sub-diagnostic set it. Generic decoders frequently get Volvo P1xxx wrong.
- Underlying throttle unit fault (see real Volvo ECM sub-code with VIDA)
- Throttle module ($200-500)
- Wiring/connector to throttle
- ECM internal
Check first: Read the full Volvo ECM codes with VIDA/DiCE (or a Volvo-capable scanner) — P1620 alone doesn't tell you the cause. Don't trust a generic decoder's literal P1620 text on a Volvo.
Source: JustAnswer Volvo V70 P1xxx list; Volvo forums (ECM-532D)