What people keep running into with vehicle diagnostics
Complaints tagged vehicle diagnostics, each raised by more than one person. One-off posts are not included.
87 recurring problems · 1515 people · 14 forums we read
Raised more than once
Most people first.
- 3RPM needle jumping and car jerking while stoppedThe tachometer gauge goes crazy during startup and while idling at traffic lights, causing the car to worryingly jerk back and forth. Despite the needle jumping, the actual engine RPMs do not drop, and the issue generally stops after revving the engine. Drivers experiencing this are often told it is an alternator problem.
- 2Gas pedal not working after wrong battery installationPutting a car battery in backwards typically blows a main high-amp fuse, cutting power to critical circuits and triggering limp mode due to low sensor voltage. This disables electronic throttle communication, leaving the gas pedal completely unresponsive until the blown fuse is replaced.
- 2Why is there a mysterious hole in my fuel tank?Some plastic vehicle tanks develop unexplained punctures that leave the tank empty, with edges pushed outward rather than inward and no metal shavings or swarf around the hole. This leaves owners worried and unable to find matching examples or explanations online, making it difficult to determine how the damage occurred.
- 2How do I read a car radio wiring diagram?Standard car radio wiring diagrams and color codes are confusing and hard to decipher when trying to install a stereo or trace electrical faults. This leaves vehicle owners stuck with a non-working radio for months because they cannot figure out which wire goes where.
- 2Serpentine belt noise in gear at low RPMThe noise occurs strictly under load between 1,000 and 1,600 RPM, such as when the car is in drive with the AC on or power steering engaged. It is most noticeable when reversing from a driveway or turning from a stop sign, but completely goes away at any higher RPM.
- 2Why do throttle trouble codes keep coming back?Persistent throttle codes and flashing electronic throttle control lights often leave car owners stuck when standard component replacements or code scans fail to identify hidden issues like voltage drops or communication errors. Without knowing how to track down these electrical faults or check for underlying wiring problems, drivers find their vehicles becoming nearly undrivable.
- 2Car gauges randomly fluctuating or dropping to zeroThe tachometer and oil gauge will randomly fluctuate wildly or drop completely to zero while driving. These erratic readings do not match the actual engine RPMs and often happen right when you step on the gas.
Comes up alongside
Topics that keep appearing on the same problems — not topics with similar names.